If the kids are training, I would get the training skis (the skis are attached, making essentially one big ski). If they are older kids, I would start them on an entry level combo ski package, maybe the obrien celebrity combos.
i own a polaris msx 140ho, its a 3 seater, scary fast and throws a decent little wake with a nice crisp peak if ya get a fat person to drive ya, i know people bash on polaris's all the time cuz they dont make jet skis any more but ive never had a problem with mine and the dealer still handles all the warranty work.
im a big fan of the seadoo wake edition. its nice to have the rope higher off the water. and also the handles on the pylon make it a more comfortable ride for the flag guy. it holds speed well and is pretty stable when pulling a ride because its wider than most skis.
i also like the seadoo wake edition..great for skating..but if you want speed to play with when your done skating the RXT is a good one..it has the pylon to get the rope up higher too...i got this idea over the winter but too cold in ohio to try but i was gonna try using the training key so that way it keeps a steady speed...someone correct me if im wrong