The first time I went to Washington DC, at 13, I loved it. I had never seen a city so white (coming from New York in the 1970s), and I found the new Metro amazingly futuristic--so quiet! And the stations reminded me of scenes from Star Wars.
The second time I visited Washington, as a slightly older teen, I found it sterile. I couldn't fathom what I'd liked about it before.
I've been back a handful of times in recent years and with each visit I find more to enjoy. On this last trip I "discovered" the National Gallery. The East Building contains a really stunning collection of modern and contemporary art. The West Building has some wonderful Impressionist works. Also visited The Phillips Collection for the first time, which is a lovely small museum, focused on American modern art--a substantial exhibit of Georgia O'Keefe abstract paintings was ongoing. Liked it so much, I joined.
I felt like I was encountering new (to me) masterpieces everywhere I went. I'd never thought of Washington as a mecca for art--museums, yes, but the Smithsonian tends to come to mind more than the art galleries. Clearly my impression was incorrect. Look forward to returning and exploring further.