LV is certainly closer for Zion then Bryce (about 250 miles) Whereas from SLC you would more likely do Bryce then Zion - (about 350miles)
In either direction you could use I-15 to speed your trip if you just want a fast route.
Alternatively you could travel from SLC via Hwy 6 and 191 through Spanish Fork, Price, and Green River then across Capitol Reef and Boulder up to Bryce. ( around 400 miles) but arguably offering more scenic opportunities than I-15
The only caveat I would put on Capitol Reef to Bryce at this time of year is the likelihood of snow over Boulder Mountain. Just watch the weather forecast.
The escape route from Capitol reef would be back to I-70 via Torrey and Loa then south on Hwy 89 at Richfield approaching Bryce from Panguitch.
Hope this helps. I have done trips to this area on a number of occasions over the last few years, and will be there myself in November from the West Coast
Best tip - Just watch the weather forecast carefully. Travel safely and enjoy a great trip.
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