I completely disagree with the PHL suggestions. It is much farther away and you will hit just as much traffic or worse trying to get there during rush hour. Not to mention the tolls. I hate driving to Philly and personally think the airport is awful.

BWI is your best option and it shouldn't take you more than 20 minutes to get there. Forget IAD for that time of day. It just isn't worth it. If you want to fly out of DCA you might consider driving to the Greenbelt metro station and taking the train from there to DCA. You can park there for free on weekends. The train ride takes about an hour but you exit right into the terminal.