Would recommend some sort of cyclo-cross w/disc brakes, maybe. Good, flat resistant tires, 700x28mm, Topeak Road Morph w/gauge frame pump. Depending on your terrain you may want an IGH(Internally Geared Hub). Shimano Alfine 8 sp generally accepted as the best option.

Anyway, I do 40 mi rt(when I'm not laid-off) on a cyclo-cross. Got it from www.bikesdirect.com for 500.00. It's got over 12,000 miles w/minimal maintenance and one minor truing. 30 mi rt is a good distance. Not too long not too short. Btw, when I got my bike it had Kenda cross tires that are too soft for pavement. I swapped them out for a set of Schwalbe Marathon Plus and have been riding on them ever since.