of course, we hit all parks. Now, I won't say we treat them equally. We like MK and Epcot the best; so, we spend more time there. If there are no time considerations or budget concerns I wouldn't think of not doing all of them. AK has been different for us each time. As an example, one time we had a wonderful day viewing the guerillas and the next time we had a better time with the tigers. If you do animal viewing the AK park is always interesting for us.
My best answer from what I'm reading into your schedule is that it might be a good idea to hit MGM-Dis Studios and AK on the same day and do your favorites only there and do the water park thing for a day, too. I feel that may be a good compromise.
Anyplace at Disney World is good, anyway. We like doing miniature golf there, too to change the pace.