From a totally recreational skiing perspective, it's understandable to try to get one ski, and a 67 senate isn't a bad choice at all. It will be big for the women but at 28 and presumably pretty recreational skiing, will be fine and probably better than what you're on. It will be a little small for someone 6'3/200, but I'm 6'4/180 and ski a 67 at 32/34 and it's fine for me even if I ski at 28/30 for something, so he'd be fine. Ski wise, if you had to choose one, I think you made a good pick.
The bigger problem will be bindings. Something like vectors are "ok" for a few different shoe sizes but likely tough for the women and larger men to get comfortably into the same one. On the rear if you all use a toe plate it might be possible to use the same one but might be tight/loose for some. The front binding is either going to be loose for the girls or too tight for the men, neither are good. Safety is a concern though and I personally don't like the vectors or bungee bindings at all. If you got a larger size rubber front binding from Wiley's, the men should fit and while it will be big for the women, might be tight enough to at least ski somewhat comfortably with. I've had small feet woman ski the same wiley's that a size 13 can fit into lots of times and they were fine. Granted, this is for recreational skiing.
So if you were forced to pick one ski/binding set ($$ tight, whatever), a 67 senate, Wiley binding the biggest foot can get into, and a rear toe plate that everyone can deal with (some are somewhat adjustable) sound like a good pick and honestly will be fine for a vast majority of skiers.
That said, it's more fun to have your own personal ski setup, the kind of ski you want, a graphic that makes you happy, and bindings that fit correctly, and is also a better way to improve your skiing if that's a focus besides just getting out and enjoying a pull behind the boat. Like the others I'd push you into getting your own skis (or women can double up). Still, if you had to do one, I still think the setup above would be a lot better than what you're on now.