You know, amyb9, there's nothing wrong with "overplanning" when you're excited ... frankly it's better than underplanning and being bewildered by the tons of stuff to do when you get there.
If you all have not ever been to WDW before, Chef Mickey's is a really fun place to eat. Every so often music plays and everyone swirls their napkins in the air and the characters come out and dance, so it is a very festive, happy place. A really good way to know you're in the middle of the magic, at last! Be sure and call tomorrow a.m. and try to get a priority seating reservation. Chef Mickey's can be pretty popular, and you are kind of arriving in the peak "spring break" season. (Wish we were going then!!!)
If you have just that night, and then the last day at WDW, IMHO you should spend as much time as you can in MK. You will not be able to see and do it all, but that's okay, you need to plan a visit back! If DS is a big roller coaster fan, Space Mountain, Big Thunder Mountain Railroad, and Splash Mountain are all in MK, and he shouldn't miss riding Buzz Lightyear. Be sure and take advantage of FastPasses! Since he's 9, MK will be special to him still, and maybe not as much in a year or two when you return... so then you can pick up MGM, AK, Epcot, etc.
My analogy of visiting WDW is that you are a master juggler, with a lot of rubber balls up in the air at one time. (which ride? which show? which fast pass? take a break? where? ) As long as you keep in mind that if a ball falls, it's rubber, and it won't break, and it won't ruin your trip... just keep on juggling! And when your heart is breaking that you have to leave, start planning your next trip and make a list of what you really want to see that you missed this time, while it's fresh on your mind.
Have a great time next week and RELAX!!! I wish you lovely weather, short lines, and lots of pixie dust!

iluvtink