We went to Chamonix the 2nd week of March last year. It was the equivalent of late season in the Rockies. While most of the areas around Chamonix (there are 4 or 5 different ones) were open, the conditions were pretty crappy. We had a great time anyway, but mid March is considered late season. Any resorts farther south probably would not even be skiable.
If the Rockies are too high, you might try Whistler-Blackcomb. It is much lower and awesome skiing.