My family spent 9 days last August, with a very similar itinerary. Some thoughts:

Homer is too little bang for the buck

Take a glacier cruise out of Whittier, if it's a rare sunny day. If not, take the short trip out to the Portage Glacier. If you take the tunnel to Whittier, hike the Portage Pass Trail if you have a a couple of hours to burn.

Matanuska Galcier hike - great way to spend a day.

Seward Sea Life Center, maybe a 1/2 day kayak in Resurrection Bay (we ran into at least a dozen bald eagles, some playful seals, etc. - great time). Don't miss the Alaska Wildlife Conservation Center on the way down or back.

In Anchorage - Alaska Native Heritage Center

On the way back from Denali - Reindeer Farm in Palmer, Iditarod HQ in Wasilla - both a nice 60 minute stop.