Snails rock. <3 snails. Love Hermits. My hermits love snails too!
My favorites right now are my turbos who decided that be damned they are gonna just go ahead and cruise around on sand.
As for snails that need flipping, plenty of species that don't and can flip themselves; just get cerith and trochus snails and that's not even a concern.
Tidepool snails (nerites, astrea, and others etc..) are the problem, can't flip, and some just crawl right out of the tank! Others like my turbos are just big and stupid (and act accordingly), but I still like em