I would probably do:
1- sportive (160km, 1.5km of ascents) Climbing road race
2- Dragon ride Wales (300km and 5km of ascent) Gran Fondo
3- La Marmotte (179km and 5km of ascent) Gran Fondo
Yeah, Gran Fondo I’d say, emphasis on sustained power. My tip for Marmotte - work on your climbing cadence. You spend most of the day going uphill, and all my TR prep at 90-ish rpm failed to prepare me for the different muscle stresses induced by spending hours between 55-75rpm.