Aquire a Milepost magazine. Great for ideas and local color. My son lives in Homer, so I agree with the rest of the people to skip Denali for now, and do Homer and Seward.
If you save Homer for last you can Halibut fish, have them flash frozen overnight in Homer, and flyout with them home as luggage. If need be, Anchorage has a freezer to keep your fish in, overnight.
Land's End Hotel, at the end of Homer Spit, has a great food bar menu. Sit on the deck and drink in the fantastic scenery. Horseback ride on the spit.
In Homer ride out East End Road. Same road Seaside Farm is on. Keep on going for another 15 -20 miles or so. Skyline Drive is also fantastic.
In Alyeska, about 35 min outside of Anchorage, there is a fun ski lift. Ride to the top and hike. Watch a bore tide come in Katchamac Bay. Many times wind surfers are out there.
You are going at a great time of year. Maybe, you will see early fresh snow in the mountains. But at someone elso said, chances are at some point you will be wet.
Many great things to do and see. It will just make you want to come back when you have more time.
When you do come back to do Denali, travel on Hatcher Pass Road north of Anchorage.