If you like to bar hop then go to Adams Morgan.
There are lots of good restaurants in Bethesda, MD. Some really good bars too (Barking Dog, Tommy Joe's)
Rock Creek Park is where it's at for running in DC. Also running around the Tidal Basin can be fun to. Nothing is better than seeing some fat/obese person walking to close to the water when you are running by. Giving them a nudge into the water is a blast (I am not kidding either, I used to run the Tidal Basin 3k every month and one month this fat son-of-a-bitch was right in my way, so I knocked the mofo into the water and kept going-I would have won the race too, but some guy named John Jordan from Georgetown destroyed me).
Stay out of Southeast and Northeast DC. Both very ghetto places. You'll likely get shot if you go there.