Columbia Heights is not TCR, unless you just REALLY want to live close to a Target.
This, on the other hand, is sound advice:
14th steer corridor NW between K and U is TCR
I plan to move back to DC within the next few years, and I definitely plan to look around this area. Might be different if I had a kid, though...
I've lived in the area for a few years and, based upon my experience, seems like there are lots of people in the area with kids. Right now, by my rough count, there are 2-3 new restaurants and 3-4 new condo projects currently in the works. This 14th street area, imo, is the best spot for trendy/not ridiculously expensive eateries in DC. Moreover, the number of high-end condo projects has really helped to clean the area up. Sure, there are a few remaining pawn shops, etc., in the area, but as far as cost/comfort goes, this area is the best. It's not as expensive, generally, as DuPont, yet offers almost all the culture/environment DuPont offers. It's not as dangerous as Columbia Heights, and finally, it's not as gross as Adam's Morgan.
Everyone has an opinion on DC neighborhoods. But if you're looking for a young-ish (read: mid-20s-30s), fun, vibrant, and cost-effective neighborhood in DC, I think this 14th street corridor has it all. If transportation is an issue, you can walk down to McPhereson for Blue/Orange, over to DuPont for red, and up to U street for green/yellow (admittedly, however, each metro stop, depending upon where you live, could be 0.5 mile walk...but then again, America is fat, in part, because people are so goddamned lazy).