I had my RAI done in September of 2004. From my experience I would have been able to drive myself, but it was comforting to have someone with me. There isn't usually a stay in the hospital the day of the procedure, I had to go through counseling that morning then they gave me the pills (I had to take 2 for the dosage they gave me). You have a half hour before you actually become radioactive. As for how you will feel, I would say it is diffferent for everyone, I actually got a very upset stomach and got sick a few hours later. If you do get sick make sure that you don't go anywhere but in the toilet for contamination reasons. After that first day I just kind of felt like I had a cold. Achy joints and tired mostly. I was also very careful about contaminating others and stayed 6 feet away from others for a week until my gieger count was at around a 5. Then I got to be withing 3 feet of people until I was in the totally free range.
Good luck, it wasn't nearly as bad as I had invisioned it would be. I hope the same goes for you!