Well the 2fer deal ends May 22nd (I think), so I don't think you'll have to deal with those 2fer crowds.
However June 13th will be pretty busy because:
-It's a Friday (this will affect mostly the evening when people come after work)
-It's summer. A lot of school will be out by then (or close to being out). That week is the beginning of the high summer crowds
-It's when Toy Story Midway Mania is projected to open. Sometime in early June (hopefully) DCA's new ride will probably open to the public, which will cause an increase in crowds.