Passportes du Soleil is a grand day out in the mountains and makes a decent start to a week in the area - given what else you've done (esp Mega) I would hesitate to recommend it as its very lame in comparison.
Trail Adiiction Destination X - guided week on natural trails - you'll see very few other mtbs
Tour Mont Blanc
Have a look for a European enduro event and base yourself around that. There is a casual "very mini" Mega in Lenzerheide in August. Riding around there is pretty good with some big days out possible if you don't mind some hike a bike and getting train / bus back if needed.
If you don't mind an xc style event why not do someof Cristalp, there are shorter versions of the main event. Then do Chamonix/Verbeir.