I have hundreds of laps at Thompson. It's the best place to go to get comfortable on track if you are a novice. It's safe, definitely not as fast as Palmer but still presents its own challenge. Great facilities there, something that can not be said about Palmer. They have been struggling to add proper facilities there.
I always recommend a day a Thompson to a beginner. It's cheap to run there and it's a great place to get your feet wet before tackling Palmer. At Thompson, you can focus on learning your car and the basic driving techniques. You can then take what you learned and head to Palmer, and your day will be more fun because you will be more relaxed out on track.
I don't mean this to be a dig at Palmer, the track itself is incredible and there's nothing like it around. It is VERY technical. I have quite a few days on that track and still haven't layed down a good lap. Other drivers say the same thing. It doesn't give you any time to catch a breath, even the "straights" have corners. Having said that, it's a really cool place that you should experience.
Oh, and the views from the top of the track are incredible. Just don't do what I did and drive off into the grass on a cool down lap because I was taking in the scenery.