Be careful of cages with a sagging floor that hits the tray below when the rabbit stands in the middle of the cage. If you feed hay or straw be sure to remove any they don't eat within 8 to 12 hours so they won't soil it. If they urinate on the straw or hay and then sit in it they can develop a terrible hutch burn or staph infection on the genital area which you might not readily notice. If they are shedding any parasites they will remain on the hay or bedding and may be re-ingested during grooming. I prefer using a hay rack hung on the side of the cage where they can pull only what they will eat into the cage.
Many breeders recommend having a board or piece of sheetrock in the cage.
Placing a piece of plywood about 12 inches square in your rabbit's cage can serve three purposes. The inherent problem with solid boards is that many rabbits are not particularly good housekeepers. If the bunny urinates on the board and then sits in it he can burn the tender skin in the genital area. More importantly, if your bunny is harboring any parasites that are shed in urine or feces, he will reinfect himself when grooming his feet which have become soiled with his waste. Keep your cages and resting boards clean with Vanodine disinfectant.