I have heavy, medium and light interfacings; heavy goes with "quilter" cotton, medium for interfacings, and light for heavy fabrics (or, I just up the lining to heavy, and don't interface the outer fabric). No need for fusibles if you sew them. I don't like how fusibles act over time.

I actually prefer 'sew-in' interfacing myself for the same reason you mention BUT when I design/write my patterns I will use fusible because I find a LOT of people are 'frightened' off by the thought of the 'sew-in' one which is a shame because I think once you get the hang of the sew-in one, you won't go back to fusible! Plus there is the added bonus....it is usually cheaper too! LOLL

I get mine from FancyWeaver on etsy http://www.etsy.com/shop/FancyweaverEtsy?ref=pr_shop They are REALLY nice quality woven labels at a really great affordable price.....and they work with you to get them just how you want them! I highly recommed them!

I have a bag making blog and would like to exchange links with others who have a bag making blog or sewing related blog of some kind! I think it would be GREAT to help each other get some footprints out there? Anyone agree?

Please do let me know if you would like to exchange links!
Cheers,
Christine

Mine is: http://www.etsy.com/shop/ChrisWDesigns I design all sorts of bag patterns and have a small BUT growing range of bag patterns which you CAN use to make items to SELL! I encourage the selling of bags made from my patterns and will even post a pic and link to your bag or shop on my blog if you wish! I hope you stop by!

Save yourselves a headache and support designers who actually DO welcome you to make and SELL items made from their patterns! There are plenty of them around if you start looking for them! Me included!
Cheers,
Christine

Hi Kathy,
You could try UniqueShiny on Etsy....I bought some of this http://www.etsy.com/listing/78956109/a-yard-of-soft-lamb-leather-fabric-u1005 and it is nice and soft. I made my "Snazzy Slouch" bag out of it. http://www.chriswdesigns.com/index_htm_files/117.jpg
The title 'says' 'soft lamb leather' BUT it isn't real leather and it it is very pliable and soft and sews relatively easy with a regular sewing machine however I did find that I got better results using an actual 'leather' needle. She has other soft faux leathers too so might be worthwhile yuou checking her shop out!
Hope this helps!
Cheers,
Christine

[*Mistake #1]

*Mistake #1 – Failing to READ through the ENTIRE instructions included with your pattern BEFORE you begin! Even if you are an experienced sewer, there are many ways different ways to construct a bag and often a designer has a different way of doing things than you do .....or a reason for doing something in a particular way that is often not obvious until it is TOO LATE if you haven’t followed their instructions! Besides....you might just learn a new technique! If you don’t like it, you can always go back to ‘your’ way of doing things next time!
*Mistake #2 –Not paying attention to the fabric suggestions included with your pattern. Most designers test their patterns in a range of different fabrics and will give you a guide to the most suitable choice for the bags design. Make up your bag following THEIR suggestions first time and then experiment with different fabrics and structural materials after you are familiar with the design! Everyone has different like and dislikes as far as the look and feel of a bag so don’t be afraid to test out different combinations of fabric, wadding and interfacing to achieve the look that YOU like however it is always best to do that AFTER you have made at least one bag following the recommendations included with the pattern!
*Mistake #3 – Make sure your sewing machine is in good order with a nice fresh needle suitable for the bag you intend to make and the fabrics chosen! If you are sewing thick denim or many layers, use a needle to suit or you will end up with skipped stitches, shredded thread and broken needles! (Not to mention frayed nerves and lots of words shouted out that you would ordinarily NOT use? LOLL) Choose a type of needle to suit the job at hand! If in doubt, check your sewing machines manual (Yes I know that sounds obvious BUT how many people actually READ their manuals?? Only if all else fails?? LOLL) Machine needles are often neglected and yet a sharp new needle of the correct type can make a world of difference to your sewing experience!
*Mistake #4 –If you intend to WASH your bag, then you should PRE-WASH your fabrics...exterior AND linings! Everyone loves the crisp new feel (and smell!) of new fabrics however if you intend to wash your bag, trust me, the look of the bag with shrunken fabrics, especially where the lining shrinks at a different rate to your exterior fabric, is NOT a good look! Of course, if you only ever intend to surface wash your bag then by all means, USE the fabric without pre-washing! If you SELL your bags, DO include a label so the buyer knows wether to surface wash only, hand wash OR toss in the washing machine!

I hope these help! I have more Bag making Mistakes to avoid listed on my Blog if you would like to know more!  
Cheers,
Christine

Here is what I wrote on my Blog! I hope this helps!

Soooo many times I get asked "What is Fleece" ..."What is it used for....do I need interfacing?" Etc etc. For some reason just the mere mention of interfacing and Fleece (also known as pellon and wadding) can make the strongest person go weak at the knees!
Interfacing is available as both sew-in and fusible and available in different weights (thicknesses) and gives support & structure to your bags and wether you use it or not depends on the weight of your fabric and design of your bag. It is almost always better to use it on major structural pieces such as flaps etc where you will find your closures such as magnetic snaps etc. In a nutshell, if your pattern instructions call for it. You should use it!

On pieces such as the bags body, the use of interfacing is optional and will depend on the look you are trying to achieve as well as your choice of fabric. Most light to medium weight fabric will benefit from it and it will give the fabric more OOMP....basically making it a sturdier and stable version of its former self!

When using heavier weight fabrics you may find it is not needed and it is important to remember that it will add bulk to your seams so if using heavier weight fabrics such as denim, bear this in mind along with your sewing machine's capabilities. Heavy fabrics and interfacing can really add a lot of bulk to major points where several seams converge etc making it difficult to sew unless you have an industrial sewing machine or other high end commercial machine....and lots of broken needles can lay testimonial to that! LOL! Speaking of needles....always use a good quality needle suitable for your fabric choice and remember to change it often! Where I have lots of layers or thicknesses, I like to use a denim needle and I almost always use a new one for each new project!

You can use interfacing on your bags lining but unless you are using really light weight fabric or wish to achieve a stiffer lining, it generally isn't needed here. Having a structured lining supporting a soft exterior doesn't often produce a good look! But again of course, it does depend on the design and style of your bag ..........and I say never say never! LOL

Yes....there are lots of different types of interfacing and fleece to choose from and brands and availability vary from country to country and making your choice can be confusing! Generally speaking, interfacings come as woven and non woven. Non woven is cheaper and gives a different, more papery feel than the woven interfacing which is the more durable and popular choice for bags.
When choosing your interfacing you need to bear in mind the type of fabric you have chosen and the look you wish to achieve....will your combination produce enough structure or do you wish to retain more drape? Will you also be adding fleece?
Medium weight fusible cotton interfacing will suit the broadest range of fabrics and is suitable for most bags. The heavier the interfacing, the more heat and pressure you will need to fuse it to your fabric so bear this in mind if using a more delicate fabric and here you might find that you need to use a Rajah cloth (A chemically treated pressing cloth) to help protect your fabric while you apply the interfacing.

Fleece (also known as wadding or pellon) is also available as both iron-on and sew-in and in different weights. It also gives extra structure and padding to your bags. I myself prefer to use fusible fleece as it is lightweight and makes it very easy to sew your pieces together. I nearly always cut the fusible fleece minus seam allowance, so as to help reduce the bulk in the seams. Mostly I like to fuse my interfacing to my bags exterior and then fuse the fleece to the interfacing. This helps reduce any occurrence of those annoying wrinkles and bubbles you sometimes get on the surface of your fabric when fusing the fleece directly onto the fabric.
PHEW! There really is a lot to think about when using interfacing and fleece but it needn't be as scary as it first appears! Familiarising yourself with the different types available helps so DO experiment with them so you can learn and get a 'feel' for which to use where, according to the look you wish to achieve! Practice makes perfect! PLUS it also helps to follow the recommendations in your pattern instructions as well and if you are unsure, ask your pattern designer. Most will be happy to help you!

Cheers,
Christine