We went to DC this past (April) vacation, and I spent over 6 months planning it. People thought I was nuts, but WE had the White House (and Capitol, and Monument) Tour, WE had the Metro tickets ready to use, WE had reduced parking for our Hotel (which was reserved at the lowest price possible), and we had a short list of about a dozen restaurants matched up to one block within each museum / monument that we were visiting. LOL!
I had a friend actually say to me "Oh, I'm more of the wing it kind of person. We've never been to the White House, though". That may be because you have to be vetted up to 6 months before your visit, which won't happen if you wing it. Mwah hah hah!
The obsessive Disney planning thing comes in handy, but I did find myself looking for more stuff to plan. I do similar for our annual trips to NH even though we have been there several times.