Luz Ardiden isn't one of the best known of the tour climbs, but if you ask me it's a hidden gem - certainly it's not an easy climb but it's up there on beauty.
Having said that, I chose it for this morning's ride mainly because KKB rode up there yesterday and said he saw marmottes. I've been a bit obsessed with these little creatures since our last trip and that was enough to make it my first choice of rides for this leg of the trip.