If Norma's in NY is your reference point you're going to be generally disappointed in DC options.
Here's
Washingtonian's take:
http://www.washingtonian.com/dining/05/brunch.html
Sequoia listed above is a nice venue on the water but the food is mediocre. Old Ebbitt is a DC institution, certainly ok, and open early on both Saturday and Sunday. But hardly great.
If my goal was actual good food for brunch I might head to 2941 in Fairview Park.