We're another family who would definitely skip MGM before we'd miss AK. As Il-gander says, for us not only is AK a full day park, we don't even get to see everything in a full day. While DS and DD (9 & 6 on our last trip) certainly enjoy specific things at MGM (playground, Great Movie Ride and Millionaire for both; Indy Show Star Tours and TOT for DS; B & Beast show, Little Mermaid and R'n'R coaster for DD) they enjoy just about everything at AK.
If you spend a half day at AK you can hit 4 or 5 of the top attractions and still move to MGM later in the day and hit another 4 or 5 top attractions there. That way you'll get a small taste of both parks and can look forward to planning more time in them on your next trip!
If you spend a half day at AK you can hit 4 or 5 of the top attractions and still move to MGM later in the day and hit another 4 or 5 top attractions there. That way you'll get a small taste of both parks and can look forward to planning more time in them on your next trip!