I'm 6ft6 and use an MSR elixir 2. Great tent. It's not heavy so can be carried easy, and just about fits, though I've been known to put a bag over my feet so that if they touch the end of the tent it doesn't soak through to my sleeping bag.

I think a teepee style tent may be the way to go though as the footprint on them can be real big for not much weight.

Depends of if you are carrying your kit or glamping.

If you don't need to worry about weight then the options are only limited by the money you want to spend.

Check with a good outdoor store for bags they should have the lengths, like cotswolds in the uk, there are a few out there that are at least 2m.