There are sites out there that list the height requirements for all of the rides on property, but I would suggest you all sitting down and looking at all of the attractions and make a plan as a family. See what everyone wants to do and make sure to include that in your planning. Especially if one REALLY wants to do something and the other doesn't, but later that one finds something... offer a compromise.
I was out in MK with my DS2.5 alone for pretty much 1 whole day! We did as much as we could! He did jungle cruise, barnstormer, haunted mansion, pirates, dumbo, winnie-the-pooh, etc. Granted with yours being older, you're looking at big thunder, splash mountain, soarin', kali river rapids, etc...
Ask their opinion and let them know what's out there before getting too crazy with the 'what-ifs'. Who knows, the family time may end up being a blast!