Above is all generally good advice.
My $0.015 (prices are down due to pandemic restrictions on travel :) )
- Think about how much time you'd like to take on the trip, then double it. There are limitless opportunities in the NW (I'm thinking, Washington, BC, YT, possibly Alberta, and of course Alaska) where one could park the TT and spend days noodling around with your tow vehicle, hiking, seeing the sights, etc.
- Think about the cost of the trip and double it. Not practical, of course, but while the travel cost is what it is, there are all sorts of paid commercial excursions that, if there's any way possible, should not be missed. Glacier cruises, flightseeing over McKinley, fishing, bear viewing, dog sled rides (that one always puzzles me to be honest), ATV Cruises, Glacier hikes, etc, etc, etc.
- Expect and be prepared for rain. If it doesn't happen, great, but be prepared.
- Bring the best binoculars and photo gear you can. Depending on one's interests, good hiking boots as well.