I think a 26" hardtail mountain bike would fit your needs. With or without front suspension, that's another thing to consider. Hardtail MTB is a very versatile and flexible machine. Put road tires on it and a rack and it'd be perfect for a road commuter and it'll work as light tourer too. Get an extra set of wheels for quick swap if you feel like going off road or use them with spiked tires in winter.

Anyway, that's what I use for commute and I'm planning to do some light touring as well.

Adam