For Prodigy setting hints, search this forum for 'prodigy settings' and you'll see 4 relevant threads (including one created by the Master of this thread, pbuck1... I'd start with that one).
You just said that you don't want travel maps and etc., but google "grand circle tour": that's the trip you're taking, except for Grand Canyon. (Taking UT-12 in both directions is pretty, but are you sure that you don't want to take a glance from the North Rim?)
The worst grade % I see for I-70 in CO is 8%, though most places list the approaches to the tunnel at "only" 7%. The switchbacks of UT-9 into Zion are only 5-6%, not bad at all. 89 and 12 to Bryce are very mellow, but I don't know about 12 East of Bryce.
While you're in Zion, leave the camper behind for a day and go up towards Cedar City: Kolab Canyons is good, Cedar Breaks is spectacular (similar to Bryce, but more 'vertical'). But, I wouldn't take a TM up to Cedar Breaks unless I had too... and the weather that high up can get really nasty, I wouldn't stay there unless I had a good weather report to depend on.
I don't know anything about the Eastern parks (Canyonlands, Arches, Capitol Reef.
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BTW, concerning 'scary' road grades: I just re-checked the % grade on Sonora Pass (in my sig), 'cause it sure didn't
feel like a mere 16% the last time I came down from there. (Even in a close-to-the-road sedan.) It's actually 26% !!! And I read on this page,
http://www.cahighways.org/105-112.html#108 that Caltrans had once proposed to dig a 7-mile tunnel so that they could turn the entire road into a 4-lane freeway. Now
that's bizarre.
We may be going
UP #108 from Bridgeport to Dardanelle, but I think we'll come back
DOWN on something easy like CA-4, CA-88, or US-120).