The conventional Sierra Nevada is rarely the most entertaining stage. The climb is to even for that. Mostly 5-7 % the whole way. Using Hazallans you would have something like a 4 km section of 11-13 %, followed by almost 20 km of 5-7 % climb. The chance for an early selection and huge time gaps would be much bigger than using the normal route.
Looking at the map, I think you can climb to over 2300m, the resorts/sports centre there, and descend to Granada. There are two routes up to that point. Ascend via Collado de las Sabinas (A-4025) and descend via A-395, the main road.
https://www.google.no/maps/@37.1140272,-3.4194016,15.25z
Agree on the French Basque Country. That would be great if they used some of those climbs. I would also like to see some of the big Catalan climbs used again, but understands that it's unlikely due to the current political situation.