Good luck Hugh. Here's the important things I learned when I was in for my hip replacement surgery:
1. Bring foam ear plugs. Hospitals are very noisy, especially if you have another patient in the room with you. It's real hard to get out of bed to smother the other guy with a pillow when he has sleep apnea snoring.
2. If you are any taller than 5'9" or so, ask for and get a bed extender. I swear, they make those beds for frickin' midgets.
3. Be nice to the nurses, but there always seems to be at least one "Nurse Ratchet" on at least one shift.
4. Watch your IV catheters carefully... if they start burning or turning red, ask for them to be removed immediately. You don't want to have an infected IV site when you have a fresh artificial joint implanted. If they ignore you, keep at them, tell every single doctor and nurse until they remove or change it to a new site. Don't let them ignore this.
5. Bring at least one good small book, magazines and big books are too bulky to read comfortably. Daytime TV will rot your brain, don't even bother.
6. Try to limit your narcotics... they will slow your G.I. transit time. The next crap you take will give you an appreciation for child birth. It may feel like you are trying to pass a bowling ball.
7. Ask ahead of time if you will need a urinary catheter. HAVE THEM PUT IT IN WHILE YOU ARE ANESTHETIZED!!!!! This is NOT something you want done while you are awake. (I had to be cath'd twice in the first 24 hrs after my surgery. BY FAR, the WORST thing I had to endure in the whole process)
8. They will get you out of bed for physical therapy probably the next day, or day after at the latest. Try to time your pain meds to be kicking in when that starts. Do everything they ask you to do, and more. I personally tried to double everything.
9. Pay attention to every medicine, any supplemental O2 you receive, any materials that are used while you are in. You will get a itemized bill at some point. I found that they outright lied on things that they said I got and the duration I got them. I successfully challenged these things on my bill.
Good luck, kick ass on your rehab. Take some pics of your scars for us!