65 channels? There's way more than that.
http://www.sirius.com/pdf/channelguide.pdf
I have the starmate replay with a home and car kit and think it's the best unit for the price that's out right now. The S50 is an ipod style with a hard drive but they have some issues with a lot of the music not licensed to be recorded so at $350 I think it's a bit too much, but if you want to be able to truly listen anywhere it's the only one that can really do that.
Sign up for the 3 day trial on the web. There's a show called sirius for dummies which takes calls. You can call them and ask about coverage in your area, but it's a satellite in space so as long as you are out in the open, it shouldn't matter where you are. I lose the signal in my car in tunnels but that happens with regular radio too.