Yes flats can be frustrating. Could it be you are riding way to the right edge of the shoulder? If so and you don't wish to move closer to the fog line or even take the lane more, then as was mentioned in an above post, the schwalbe marathon plus should do wonders for you, they are harder to remove and replace, but the likely hood of a flat is greatly reduced. Leaning how to fix a flat is a worthwhile and easy skill to learn btw.