Living in DC, I find Baltimore to be a good blue-collar alternative when DC gets to be too much. The Inner Harbor is a development nightmare (think Hard Rock Cafe), but other sections are still interesting. It's a weird city -- gritty and gothic -- with some of the worst ghettos I have ever seen, but there are highlights.
[WS:] Baltimore, as an alternative to overpriced DC housing has been pushed by developers for a couple of years now, and it led to revitalization of vacant industrial lots along the waterline aka "Harbor East." However, the city is a transit nightmare - it is a gigantic gridlock with grossly inadequate transit system and Annapolis politicians determined to keep it that way. I suspect that it is the way of enforcing apartheid in the region - it impedes the mobility of the urban poor (mostly Black) to the burbs. Unlike New York that is served by regional rail system, Baltimore doe not have a good rail connection to either DC or Philly. The MARC service is geared toward delivering commuters to DC, not to Baltimore, and it does run on weekends or late hours. The only rail connection to Philly is Amtrak, which is quite pricey on NE corridor ($40 one way - mainly to milk Northeastern states to subsidize rail service in the south and Midwest.)
For these reasons, I do not think that Baltimore is a true alternative to overpriced DC housing market. Housing is much cheaper here, but transportation is a nightmare, especially to DC (the reverse commute is not that bad, however.) With the collapse of the housing market, I am waiting for the other shoe to drop, and Baltimore returning to its gritty grimy self.
Wojtek