XM and Sirius are pretty much the same now since they merged. You can look at the various packages available, but it's pretty much all the old sirius channels with a few of the "best" XM stations still around. I had XM before the merger and there wasn't really a whole lot I missed afterwards, except for how they changed the format of the uncensored comedy station (went from playing really long segments of comedy sets to really short portions)
Check out any of the "dock and play" radios at sirius.com. When it was still XM radio I had one that I used both in my car and in my dorm room, I'd just take it with me. I had a little antenna that I could run the chord through the backseat of my car and stick to the top of my trunk with a magnet, and then I had an antenna in my dorm room as well. I'd just plug it in and had no problems. There was no permanent installation I had to pay for in my car, it took less than 5 minutes to run the wire, and I never even put a dock in my car, I'd just rest the radio in a cup holder.