I spend 90% of my time and miles on a 2010 Kona Dew Drop. I liken it to a crossover SUV of a bike; 37c tires, MTB style frame, but drop bars. Avid Disc brakes for bad weather confidence. Not for real off roading, but it can definitely hang ok on the tow path, and get through crappy pavement with no issues. Yesterday I forgot I was riding heavy, and crossed a speed bump at pace, which shook my panniers, but didn't even give me a wiggle.

As my backup I have a late 90s era Kona hardtail MTB. I've thrown a cheap rack on the back, but I have to say it doesn't play nicely -- I experience some heel strike, so I mostly use a back pack when I ride it. I also prefer the variety of hand positions provided by the drop bars, so I think before winter I'm going to either get some drop or ergon bar ends, as I expect to use the MTB more this winter. The funniest thing about it is I've actually managed to do my shorter rides (under 10 miles each way) somewhat faster on the MTB, I think because I can power over the rough terrain a little better, and I don't even think about most things that might constitute 'obstructions' on the Dew Drop. It also accelerates a little faster, probably due to lower weight, smaller wheels, etc...

I recently acquired a Specialized Roubaix which I intend to be my 'fun' bike, but I expect I'll do some light commuting on it next summer.