Stop at the
Little Big Horn National Battlefield. Well worth a day; it's historic and beautiful.
Also,
the Big Horn County Museum is really interesting.
Both of these are off I-90, between the Wyoming state line and the I-94 junction.
Marias Pass on the south end of the park is expected to get up to 5 feet of snow in the next 2 days. Logan Pass may not be open until late July this year!
But there is lots to see even if Going to the Sun road is not open all the way across the park. Well worth going.