I think it would be lovely plain with a sweetheart neckline, or, even a square or v neckline at the front and you can still retain the jewel neckline at the back?
Is your fabric patterned or plain as that may help you decide? I think a sweetheart neckline goes with any plain or patterned fabric. (Can you tell I like a sweetheart neckline . . . I think it suits everyone.)
Best wishes and great sewing.