I buy whatever I can get cheapest. Flats are not a problem around here. Just this week I saw the first broken glass on the road that I've seen for probably 2 years.

I guess good tubes couldn't hurt, but it seems to me that anything that gets through the tire will eventually work its way through the tube, unless it's something that has a limited depth like a goathead or a thumbtack. I'd think going with something like Marathon Supreme tires would be a better defense.

They do make thornproof tubes with extra thick outside walls, it might be worth getting a pair and trying them.