We've just driven Col de la Cayolle on the Route Grand Alps, we had to go that way rather than Col de la Bonette due the Bonette still being closed due to snow (bad luck or poor planning, you choose). Anyway, both these passes form part of the Route Grand Alps and run North/South roughly along side each other. Having now done both I can really recommend the lower of the two passes the Col de la Cayolle, I know its not so high but it sure does have it for drama and variety, I really recommended it