I opted to have my bridesmaids each pick out their own pair of shoes to go with their dress. The only requirement was that they had to be silver. From what I have seen, most of them aren't opting for flats (which is totally what I would do). My thoughts: several inch heels + hours of pictures + hours of dancing = painful and tired feet.
I decided a while ago that I would probably just pick up a pair of plain silver flip-flops for each bridesmaid just in case they wanted something to change into at some point during the night.
Yesterday I read about an awesome deal to get them at Target for FREE - yes FREE! They were going on sale at Target for $2 a pair and there was a $2 off per pair coupon.
How did I get enough coupons for all 5 bridesmaids? Helpful hint: you can generally print out 2 copies of the coupon per computer. For me that usually means using my laptop, my fiance's laptop and the desktop.