Wow. Looks like a epic family vacation that everyone will remember for the rest of their lives.
A few comments:
1) the SD zoo is amazing but you are putting a lot of extra miles in the trip to go there. Would you consider a separate vacation of just SD? (flying obviously)
2) Glacier is beautiful. You may want to go from Coeur d'Alene to Kalispell or West Glacier so you have a full day there. The Going-to-the-sun road is consistently ranked as one of the best drives in the US. (Tow vehicle only - no RVs). It means your driving days on either side are longer but your sightseeing day is completely open.
Enjoy your travels.