+1 on specilized armadillos or continental gatorskins. I've definately gotten fewer flats since using them (thanks ATN).

when riding in glassy areas, its good to keep an eye on you wheels for bits and pieces of glass that are in the process of working themselves in. oftentimes the first pass will stick the glass part way in, and the subsequent passes will press it in towards the tube. if you run over a glass patch, its good to stop and check your tires.

riding on hiways is stressful. I'd not do it without a shoulder. with a shoulder however, it will still probably have debris and vibration that a normal road wouldn't.