Here are some miscellaneous ramblings:
When you go to the dealer, watch your kids closely to see what they naturally gravitate to -- some kids seem to get a charge out of paddling and find pedaling rather boring.
Having three different boats is nice because you can trade around to accommodate speed differences, or occasions where only one or two of you are going out and you have a selection to choose from (BTW, the tandems are also capable single handers) and can accommodate lots of gear, dogs, etc.
Since your family are avid sailors, you'll find the sailing kits great fun and they increase the versatility of the kayaks as well. They won't hold a candle to your cats, but rigging takes all of two minutes and they're amazingly versatile used along with the pedals in light winds or even upwind!
Don't overlook the Sport -- it is light weight, maneuverable, has the fishing trays -- adds a nice diversity element to your "fleet". If you're the fastest peddler, you can put yourself in the Sport and give yourself a handicap!
The Oasis would be a good choice for keeping the kids together and with the group. You can also mix it up with one adult and one child in the tandem and let one of the other kid go solo, etc.
The Revo is the most versatile, and IMO, the best sailor out of the box. On the other hand, the Adventure is the fastest, the smoothest riding, if a little wetter and slower to turn. Somehow, I think your kids might like it (it should be able to accommodate their size). It's my personal favorite as well.
In summary, it would be hard to go wrong with a Revo, an Oasis and either a Sport or an Adventure with a couple of sails!