An not so well known gem around DC is the Gaylord National in National Harbor. It is south of the city - but they have this WONDERFUL ice show every year. Although you don’t have to stay at the hotel to see it - if you do stay at the hotel - you get front of the line access - which is great as the line gets long FAST.
So it basically takes about 20 minutes and no matter how warmly you dress - they give you a jacket - TAKE IT!!! But there are all sorts of wonderful ice sculptures and ice slides (yes even adults can do them!!) So if you are looking for a fun little retreat - check out the Gaylord National