I usually use buttons...if you have a basic yoke skirt pattern, cut it out in about 1-2 sizes larger than normal, then sew the right seam with a big seam allowance and finish the left sides with 1/4" or 3/8" seams. That should give you enough room to overlap and put buttons down the left side.
Another option is to cut a strip of fabric about 4" wide and your waist where you will wear the skirt + 4" long for a waistband. Gather a rectangle of fabric to this (you can sew two rectangles together for front and back if you need more fabric) and make buttonholes in the waistband, then down the left side. Or, put the buttons in the front. Heck, put 'em in the back if you feel like it -- just watch out when you sit down! You can also put just 4 or so buttons down the side and sew the rest of the opening closed.
I've seen skirts on here that fit by means of lacing. Make a tube for the yoke that will pull on over your hips, then use buttonholes, lacing tape or what have you to put lacing on either side. Tie lacing to fit. This works best with drop-waist skirts that have gathers that can absorb the extra fabric from the lacing, but I think it would work with a straight skirt too, if you put in the lacing curved to allow for the hips. I wish I could explain that better but you know....
If you want something easy with no elastic, wrap skirts are an option. However, I find that they fit oddly on me because I have huge arms and legs and no meat on my torso whatsoever.
Hope this helps. I avoid magnets and velcro because personally, I'm a spaz and I'm afraid of my clothes falling off....but those are options too.