We have done MGM and AK on the same day a couple of times as neither are our favorites and we just hit a couple of places. We usually spend a little more time in AK. You won't be able to do everything in one day though unless you are going all out commando style than you will probly still miss some thins as there are a lot of shows to watch although not many rides.
I agree with the AK and MGM suggestions. Go to AK first nice and early so you can catch the Safari first thing. I always think early morning is a good time because the lighting is soft and the animals are out and eating! Then go over to MGM.
Some things that would influence your chances of doing it.What Time of year or dates you are going?That will enable posters to be able to judge crowd levels and park hours.Armed with that information can give you solid advice on how to get the most out of hours you have tour on that day.
I know this is slightly off topic but...
A few years ago, my Brother got a bunch of special one day park hopper passes for his volunteer work he did. He took all of his bros and wives. We went to MK, EPCOT and MGM in one day! Of course we didn't do everything. We hit the mountains in MK, TOT and something else in MGM and a few things in Epcot. It was a mad race to cram as much as we could in one day! It was fun though~
Hit AK early in the morning and do the safari first thing. If lines are long, fast pass anything else you might wish to do. If not, enjoy your time ; ) Map out a plan for the day and try to leave around 2:00. Then hit MGM before 3:00 - just in time for the afternoon parade. Check all of the show times and make a schedule. Fill in the blanks in between. Don't miss Fantasmic! This is a totally doable plan. We have done it many times.
Definitely the AK and Studios, in that order. There's a free touring plan from the Unofficial Guide that does exactly this, available at allearsnet.com.
Befuddledlife welcome to the Dis While I agree with the Studios/AK combo, I will suggest something bold: Blow off the non Disney parks! Stay at WDW the whole time and do a really comprehensive tour of what WDW has to offer.