A nice hotel in an intriguing area.
My daughter and I stayed at Hotel Palomar Washington DC (Dupont Circle) for a total of two nights in July of 2012.
It was a perfectly fine stay. The staff were great, and greeted us warmly and efficiently. I was impressed to hear one of the staff using excellent French to converse with the French-Canadian couple checking in ahead of me. He jokingly challenged me to give it a whirl and I managed not to embarrass myself too much (at least that's the impression he gave). Merci!
The hotel itself actually struck me as a bit dated. Some of the furnishings and trim looked a little worn, moreso than I would have expected. But to be fair it's also a very busy place so maybe that makes some maintenance issues a bit more of a challenge. The room we had was equipped with one very comfortable king bed and was generously proportioned. No view to speak of but we didn't spend a lot of time in the room anyways so it didn't matter. The AC was effective, an important consideration given the smokin' hot (and humid) weather. 
This hotel is located near Dupont Circle. I was told by hotel staff that it'd be less than $10 to get a cab to/from Union Station, but $15 was actually what it turned out to be. Not a big deal, but just something to be aware of. There are many interesting little restaurants in the same block as the hotel, serving everything from Afghan fare to sushi and lots in between. Probably one of the most fun one was Bagel's Etc, right across the street. If you want to see 'bagels etc' dished out at hyperspeed this is the place to go. In the Dupont Circle area itself (a block or two away) there are many more interesting establishments. With respect to other venues, it took us about 30 min to walk to the National Zoo but there were fun things to look at on the way. If you've got younger kids, though, consider a bus or a cab...it's mostly uphill.
Access to the Mall and the tourist highlights was easy using the subway station located at Dupont Circle. Have a look at the transit web site first so that you learn a bit about it, as I ended up spending money on a "fare card" when I should've bought a "SmartTrip card". Not a big deal, but save yourself the aggravation. The metro was generally efficent but ensure you have a system map with you as the routes are not well marked in the trains themselves and the drivers seem to mumble a lot, so it can be a question as to where one is and/or going. But...once you get that figured out staying in the Dupont Circle area won't be an issue.
Enjoy your stay...we did.