Be sure to drive the Going To Sun Road to the top, and if you're
up for hiking there is a great hike at the top of the road. Reallly beautiful area. Or take the shuttle that's offered, if you'd rather not drive the road. Sorry I have no food-stop recommendations for the area...we were on a cross-country trip in our motorhome at the time (2002) so we were doing lots of cooking on-board.
Make sure your camera is charged up, lots of amazing scenery in that area. Also, you'll likely want to dress in layers that you can either shed or add on as the temps can vary the higher you get.