Get in touch with Tri4thealps- did ten days with them last year.
They may be happy for you to tag along on some guided rides and the pace is good (there were two pro triathletes out there last year – look up Brad Kahlefeldt – he can ride a bit!)
The avoriaz via montriand loop is good but only about 80 mins even without killing it.
Joux plan from sameons is good.
Down to lake geneva and round the lake is good (although circa 160 miles without a lift back!)
Ride over to flaine and up that climb is good.
You’ll have an awesome time – roads are amazing.
James