Driving only 4-6 hours/day doesn't leave much time for sightseeing at Yellowstone, Glacier or Grand Teton. Your two Roadtrippers routes indicate a total 121 hours of driving to get to the wedding and back again. At 6 hours/day, that's 20 days of travel with perhaps short stops for sightseeing along the way. With three days for the wedding, you have seven days to divide between Glacier and Yellowstone. Two days for Glacier, three for Yellowstone and a day trip to Grand Teton would be reasonable. Of Course, if your "about 30 days" could become 35 days you can have a much more relaxing trip.
