Never been a huge fan of fake plants but I'll definitely look for some good quality ones. They would like nice in between the stones!
I've found that PetSmart has some highly realistic individual small plants. Especially if you trim off any fake "root" looking stuff. If you want to see what I mean, check out my most recent photo of my tank in my thread, Final Tank Setup. All the small sized plants are from PetSmart, and they look great.