I re-upped with the $29 for 6 months offer. Between driving to work, road trips, and having my gf in the car - the Sirius options are just too convenient/easy. She has her stations for when we ride together, and I have mine.
With that said, I have a calendar reminder to call and cancel a few days before the 6 months ends. If I'm keeping it, there's no way I'm paying full price. I use Pandora, Soundcloud, NPR on FM, etc. enough to fill in the gaps.