I was in the US a few months ago and did experience what you are talking about on the interstates, so I get where you are coming from. It was actually kind of a strange experience to be out of service so often.

But here in Canada, where I spent almost all my time, the only place I've ever had any significant coverage issues is when I was in the far north, and I've only been there once. It's essentially a non-issue for me.

The only times I use my iPhone for music are on long drives and airplanes. Not a good use case for iTunes Match. I do have Match, but mainly just use it on my laptops (which don't have any music on them).