Bellingham/Airporter Coach runs buses from Sea/Tac and downtown Seattle to Bellingham but you would still have 35 miles more to the trail head from there. There was a dinky tour operator last summer taking tourists from Bellingham up to Mt. Baker ski area in a van but I haven't seen them this year yet. With 4 people a rental is probably cheaper and the best option. The town of Glacier is real close and has a few B&Bs to stay at, and a couple gated ski cabin resorts you might be able to rent from. Search the web for info. Only motels would be in Bellingham. BTW. You got to buy a parking trail pass if you drive to trailhead.