Sanny wrote:
Bob Edwards of Morning Edition fame is on Sirius! I miss that growly baritone in the morning.

Bob's on XM. And unfortunately, his growly baritone is a little tinny, due to the sledgehammer compression on most of the talk stations.
Sirius does have generally better offerings from NPR at large, but after he got fired at NPR (stupid, stupid...) Bob's an XM guy.
Air America: They recently signed an exclusive deal with XM, so they're now off Sirius, and XM's "America Left" channel is now officially branded "Air America".
(I also occasionally listen to America Right (know thy enemy...) (just kidding, you loveable Rapture Righties!), and I find it highly amusing that the 10-character limit on the MFD truncates the title of the Rusty Humphries show to "Rusty Hump")
KTPhil - Long term committment: Not on XM. Dunno about Sirius. In fact, my sibs and I bought an XM receiver for our folks, and I put them on my Family Plan even though they live far away, so they only pay $7/mo instead of $13. That's a nice savings, if you have multiple family members who want to join and someone's willing to pay the whole bill, then get reimbursed by everyone.
Gagendel - Sirius prolly does have marginally better mobile coverage, since they have 3 sats in a constantly-moving elliptical orbit. The XM in my car rarely drops out though, so I'm happy with it. On the other hand, if you have a Home Kit, XM definitely has better home coverage with their fixed-orbit satellites, so you don't have to chase the signal with your home antenna, which is a problem a friend of mine has with Sirius.