In Marie's Getting Prepared for a TKR post, I agree with her that preparing your living space is an important thing. Not doing so can really cause problems. At first, I thought steps were going to be a problem, but I didn't have to worry. Going up I can do, but I go down backwards. The rehab center's physical therapists agreed with me when I said that I'd be able to better use the steps after the other knee was done.
Don't forget the bathroom. A commode chair with handgrips and a shower seat can help BIG TIME! Bed Bath and Beyond may have a grab bar that uses suction cups. You can get a handheld shower head as well as a tub bar. Plastic lawn chairs are great. I used one when I had my arthroscopy on both knees in 1994 and 1995. Check ebay and Craigs List including other auction/seller sites, but be careful of what you're getting and ASK QUESTIONS of the seller.
All these things can be picked up over time before the surgery. Sure, it might drive some people nuts, but it's going to save them from having to deal with you when you need help most.