If it were me, I would spend my time in Seward and Denali. The fall colors in Denali will be incredible that time of year. Maybe arrive your first day in Anchorage, next day drive to Seward (3 hours), day 3 take 6 hour Kenai Fjords (the shorter tours don't get out of the bay), day 4 Sealife Center, Exit Glacier or other activities, then drive to Talkeetna, overnight. Don't try to drive from Seward to Denali in one day. With traffic, construction, slow RV's, accidents, etc. it could take you up to 12 hours. Plus, you need to stop in Anchorage or Wasilla for some grocery shopping for your Day 6. No food or drink available in the park, so you need some snacks and food for your trip into the park and these two cities are the best places to shop. Basically convenience stores and small, expensive markets after that.
Day 5 to Denali, afternoon near entrance (visitor center exhibits and film, sleddog demo, drive first 15 miles of the road, light hiking), day 6 all-day shuttle bus to Wonder Lake, day 7 drive back to Anchorage, usually a red eye flight home. On the way home you can do a glacier hike on Matanuska Glacier at 2pm (lasts about 90 minutes).
http://micaguides.com/hiking.html
If you have an extra day, you can spend an extra night in Seward or Denali. If in Seward, you can do the glacier hiking with Exit Glacier Guides. Glacier hiking is incredible, but I would not do it without the proper equipment.
A rental car will be expensive booking this late, but well worth it to make the most of your relatively short time. Or you could train to Seward and back and just get a car for Denali (very hard to get around near Denali without a car and with no car, your lodging is limited to those with a shuttle service to the park).
Seward has the Holiday Inn Express, a Best Western and other hotels. Anchorage has quite a few chain hotel hotels. Quite a few options near Denali too depending on your budget and desired amenities. Personally I like rooms with some sort of kitchenette or at least a fridge and microwave to cut down on some of my food expenses (eating out in Alaska is not cheap).
If you stay in Trapper Creek, rather than Talkeetna, there is Alaska's Northland Inn, which is a nice place with two 2-level apartments at a fair price. Talkeetna has several lodging options and is famous for flightseeing tours into the park (which you could do the evening you arrive and if canceled due to weather, reschedule for the morning of Day 5).
Heading to SE Alaska on Saturday for my 16th trip to Alaska. Can't wait!
John