We did the battlefield one, not the town, the guide drives your car around the battlefield and other sites. It was ok, but his information seemed rather canned and left little time for questions, extra stops or staying in any one place with only enough time to take a couple of pictures. I know he had to stay on the schedule, but we would have like more time some places and less on others. I'd recommend going to the visitors center, which is great, for orientation first and then using the map you can get there to tour the sites on your own at your own pace. I think the same would apply to the town tour. Gettysburg is very small and it would be easy to see the sites on your own.
We stayed at the Farnsworth House Inn, which is famous for being haunted. We didn't see the ghost, but it is a fun place to stay! At least go for dinner, the food was very good with local specialties and the dining room has nice, Victorian decor with lot's of antiques.