DJB: Yeah, forgot about the Tricross, IMO it's a good option. The main thing is that up until a few years ago, cross bikes were used very frequently for touring; lots of people successfully crossed the US on Bianchi Volpes, for example. There are lots of cross bikes made more for general use than for racing.
Originally Posted by AdamDZ
I mean, Surly Troll. Or a Big Dummy or other Xtracycle?
None of these would be my first choice for the OP's usage list.
Troll is more for offroad, and the OP is mostly discussing asphalt and gravel. BD/Extracycle is great for utility cycling, but isn't anywhere near as versatile as a standard bike plus a trailer.