Since you are already in SoCal you won't find DC much different except you'll get snow, but no earthquakes, mudslides, or brush fires. I've been here for almost two years and like it. Here is the short of it, in my opinion. Its fun if you are single, not so much if you are married with kids unless you are loaded with cash. Housing, both renting and buying, is expensive everywhere unless you live way outside the metro area. If you do that then your commute will suck.
On the good side, there is no shortage of things to do. I think you could live here for 20 years and not do everything you want to do. Restaurants, bars, museums, theaters, outdoor stuff, monuments, sports, etc. And thats just DC. NYC is a few hours away as well as Baltimore, Philly, eastern shore, blah blah. Also, I personally like the climate. Sure it can get very hot and very cold but its four seasons so winter is usually done by Mar/April and summer is done by Sep/Oct.
As far as people go, you get the whole spectrum of society. Most people here are all from somewhere else. LOTS of singles because of all the companies and the Capitol Hill crowd. But that also brings a lot of self important morons. "Oh I work for <insert senator>".
So in short I enjoy it here and will be staying for the forseeable future but I don't think I could live here for the rest of my life. Lots of people like it and lots of people hate it. Just all depends.
"Ray, when someone asks you if you're a god, you say YES!"