Hwy 12 is great and you shouldn't fear it however if you feel you or the wife wont be able to handle it so be it obviously that is up to you and your choice. 62 is fine nothing wrong with it. You will find it is actually shorter and faster than 12. I used it several times this year less traffic for sure it is still a pretty road just not anywhere near the same class as 12 and totally different type of scenery.
If you do take 62 do make sure and take a day trip from Bryce to Boulder or even past it. 12 is just such an incredible road for scenery from Escalante to Boulder it is eyeball bustin' stuff. You could also hit Kodachrome Basin on the way back (or any other afternoon you are in Bryce it is not far maybe 25 -30 miles from Bryce), and the Boulder Mail trail over Hell's Backbone, and at Boulder take the Burr Trail out to the Waterpocket Fold. That gets to be a long day but otherwise you will miss some of the best scenery on this planet. If I had to cut one of those out it would be the Boulder Mail Trail while neat for sure and historic it does not have near the beauty of an out and back on the Burr Trail.