Our first trip was west (starting at the Canadian border in Sarnia, Ont.) on I-69 to I-94 to I-80 to I-76 to I-70. So we passed thru MI, IN, IL, IA, NB, CO, on our way to UT and AZ. The I-70 portion is especially striking through the Glenwood Canyon. There are numerous truck stops (Flying J, T/A, Love's, Pilot, etc.) where there's almost always a dump station for RVs. We don't drink/wash in our on board water, it's just for the potty, so pretty much anywhere to refill our water works for us. I also believe all the NPS camping areas have dump/water stations or potable water available, although later in the year not every amenity is always available, so you might want to check each Nat Park online first just to see when their "seasons" are, and what isn't available during your time frame. We stayed in Moab at a commercial campground right at the CO river bridge (think it was called Riverside Oasis CG, go figure
). The serviced sites were full, so we took a tent site for $20/night. It was fine for us. We did a day at Arches Nat Park, but didn't make it to Canyonlands or the other area places you've mentioned. Bryce Canyon NP is definitely worth a side trip for a day/night, for the scenery. The food at Ruby's is pretty good. Try the pot roast entree if available, it's quite good. Then we went on to the GC NP south rim for a couple of days, as the north rim is closed fairly early in the year due to weather. As I've recommended before, it might be worth your while to get a NPS Annual Pass for $85, early (first week?) in the month you're heading out. It's then good until the end of that month next year, and it gets you into any NPS, BLM, NRA, NSS, etc. - doesn't cover camping, but if you're an American senior, it discounts it I believe. We got one at GCNP last year and it's reduced our entry costs to less than $5 per visit. Some parks charge $20-$25 per day/week, so it can save you money.
We're thinking of heading back out there around the end of September, so we might see you. ynk!