Thanks for the responses - good info and we appreciate folks with local knowledge sharing their expertise.
The GS Travel Planner had us going north of Cedar Creek on I-15 then across to U.S. 89 on Hwy 20, then back south to 12.
We've decided to stay at Kodachrome SP. We have budgeted 2 days before we head for Colorado so we might not get down to Zion - depends on how much time we spend at Bryce canyon, but, it's all good!
We like the idea of driving Hwy 14 instead of 20.