Are you driving? A lot of people like Homer, but I'm a Seward person myself. There are always otters, and sometimes the occasional seal, by the shore and I can watch them for hours. The scenery is gorgeous too with the mountains crashing right into the water. The museum there is ridiculous and tiny, but plays an interesting movie about the earthquake and subsequent tsunami of 1964. The hike up to Exit Glacier is challenging, but worth it, and it's one of the few places you can easily access ice fields. If you really want to play tourist, I've never been disappointed by their scenic wildlife tours. If you go, I suggest doing the 8-hour one out to the big glacier (can't remember the name).
The thing about Alaska is that there isn't a lot "to do" the way there is in typical tourist destinations. You just have to be outside and look at things. Three days in Denali might be rough if you're not doing a pass into the park every day. I would recommend doing the basic on and off pass instead of the fancy tourist bus. It lets you hop on and off all along the road, so you can hike at your leisure. 49th State Brewery in Healy is good food, and has the Into the Wild bus, which is always amusing.
In Anchorage, I would plan to spend one day on Turnagain Arm. The Winner Creek Trail behind Alyeska Resort in Girdwood is one of my favorites, though you might be bored of giant trees after spending time in Southeast. The Double Musky Inn is a must for dinner. I have a bizarre love for the Alaska Wildlife Conservation Center. You'll probably see a lot of Alaska animals out on your adventures, but it's nice to get to see them up close. It's also only 10 minutes from Portage, which has some great glacier viewing.
I just moved away from Anchorage last winter because of Alaska's failing economy, but if you have any questions about your plans for Anchorage/Homer/Denali, I'd be happy to help!