There are not many "thrill rides" at MK (other than the "mountains"), so just about everything will be safe if you check the name. There are definately some classics that I wouldn't miss.
Pirates of the Carr. (you or hubby first go down to the Jungle Cruise and get a fast pass for is while you go over and wait in line for Pirates, then once you are done, you will be able to pretty much walk onto the Jungle Cruise).
Jungle Cruise
Cut through next to Aladin and you will come out right by the Country Bears
From here, hit Fantasyland (again - use fast pass if you can - get one for Philharmagic and then hit other rides in the area while you wait). Philharmagic, Its a Small World, Peter Pan, Pooh, Snow White and the twirl and pukes...errr the Tea Cups are all in this area (you do spin in the tea cups, but its makes me sick when my boys try to really get the tea cup going fast).
After that, hit Tomorrowland and the race cars, Buzz Lightyear (a cute ride for young and old), the Transit Authority and the Car of Progress if its open.
Spectromagic is not done every night, so I hope it is going on the night you are there. If so, get yourself a spot on the curb and once its over, try to get to a nice view of the front side of the castle - down mainstreet is a great place - or other areas like that to watch Wishes. It is fantastic!
I am not sure if your
ECV MiL will be able to transfer, but you will want to stop by guest relations to get a special card if she is truly bound to her chair. If she has a medical reason (versus it being able to help her walk more during the day, etc), then she will get a special card that will allow your family to enter rides together with her through the handicapped entrance. If its more for convenience, some of the rides are now big enough to accomidate people IN line, but most will still offer you all sorts of assistance.
I hope you have a blast on your trip. There are other things you can certainly fit in if you find time, Aladin is cute (much like Dumbo), Dumbo is a classic but usually has a long line, the show in front of the Castle is really all that is there (unless you meant eating in the castle and if you dont have a ressie for that now, I am not sure you will get one at this late date) but we have enjoyed it occasionally over the years, the Tiki Room is a fave of ours, but many like the original better, Toontown is full of characters for meet and greets, but mostly set up for children to enjoy.
Have fun!