I would say having 2 weekend vehicles ( T2 and MX5) would be a stretch for a family, I say that as a T2 owner myself, good fun but if you are relying on that when 3 of you want to go anywhere together would get tiring quickly.
I like the bangernomics idea, you can get great cars for not much money these days, maybe something like a old A4 convertible for open top family driving.