Anybody else want to slag on our town who doesn't live here or who only lived here for a couple of years?

Call it the local's revenge - like a college town or any other itinerant town - you'll find it takes more than a couple of years to get to know the city and its citizens. So, definitely seek out the advice of locals. I second the recommendation of bikewashington.org. You might even consider joining their mailing list for a few days as that membership is full of local knowledge of the bike scene.

Riding in the city is great fun; you might want to seek out the advice of some of the DC folk on the singlespeed forum if your idea of fun is decidedly urban -critical mass, bars where you're likely to run into other cyclists, etc.