Yellowstone and Glacier in May

Heavenbound wrote:
After hearing what you all had to say would it be better to go in August? August is wide open for us. September could be done but it conflicts with some classes my girls will be taking.
BTW my kids are 3 girls 15,13,10 and one boy 9.

Far more will be open in August. There's been good snowfall in MT and WY this year, so it may take a while to melt out. My mother used to work at Hamilton Store near Old Faithful and she had pictures of the store in mid May with 6'-8' drifts they plowed through to get into the store. Also, many school districts now start in late August so the crowds begin to abate by that time.

While one can get along well w/o reservations at Grand Teton and Glacier, you should really consider getting them at Yellowstone. A very busy park and the non-reservable CG's can be filled before 8:00 a.m.

As noted, one needs a fair amount of time in Yellowstone. We went there again last summer and spent a week and still had a lot more we wanted to do. And we've been there four times before. Driving through the park is slow, not only because of the speed limits, but because there will be traffic jams caused by bears, moose, elk, bison, etc.

Be aware that a large swath of the forest on the west side of Glacier burned last summer so you'll see miles and miles of blackened trees.

Personally, I wouldn't try to add California/Oregon to this trip. Sure, you can drive it, but wouldn't your kids get a lot more out of the vacation if they spent time actually seeing the sights rather than being cooped up in the MH for many hours and many days. By the time you add in the Black Hills along with Grand Teton and places in between, you're already looking at a very rushed three weeks from PA. Last summer from CO, we took 2 1/2 weeks for Grand Tetons, Yellowstone and Glacier NPs.