Check out the Summer Teacher Institutes at the National Gallery of Art.
They are approximately 5 days long and are thematically based. The year I
went ( 1987-the first year I believe) the theme was 18th and 19th C.
American painting. It was fantastic! We attended lectures and then went
out into the galleries to view the originals. We also visited other museums
in Washington. They provided us with wonderful slides and other resource
materials. This institute is interdisciplinary based so you will meet and
work with teachers from other disciplines as well. They may already be full
for this summer. You could contact the Education Dept. and get on the
mailing list. Good luck!