M.M.
IMO the best place to see Santa is next to the National tree. The National tree has a train running around it along with a tree representing all states and I think territories. Just a short walk from all of that is Santa's Workshop where you can see Santa for free and take your own pics. The Santa has always been real nice and looks great. Background being in the workshop is nice for the kids too. I've always gone on Friday nights about 6 and never really stood in line long.
I second the trains at the Botanic Gardens. Great smell with it too. On Thursdays they have people singing holiday music.
Something I learned last year is the laying of wreaths at cemeteries. The most popular one around here is of course Arlington, but all of the cemeteries do it to thank the veterans. Something to consider when thinking about the holidays.