The thickest stuff you can find. Briars and thorn bush thickets are great. If you can find and overgrown apple orchard, rabbits hoard in them. Slues are also great places along as cut-overs. Any THICK THICK THICK will hold rabbits.

I assume you are jumpshooting or still shooting them, meaning you aren't running them with dogs. If so, some of these areas may be hard because you will never see a rabbit just walking and trying to find them.

Good luck, post your results!