I would suggest that you seriously consider adding a leg on the Alaska Railroad into your trip if the timing would work.
Last September we spent a week in Alaska, half in Denali and half in Anchorage and points further south. The relevant portion of our trip for you would be the following:
Drive from Anchorage to Talkeetna, do the jet boat tour with Mahay's Jet Boats. Drive from Talkeetna to Denali State Park, overnight at Mt. McKinley Princess Lodge ($99/night, great views). Depart SOUTH the next morning to Talkeetna, catch the train from Talkeetna to Denali National Park (3 hours and $60 per person each way, and some of the most amazing views anywhere).
http://www.alaskarailroad.com/arrc18.html#6 and
http://www.princesslodges.com/mckinley_lodge.cfm
Another really fun thing to do is snowmachining, which is offered in the summer via a helicopter flightseeing/snowmachining trip. I always use Glacier City located in Girdwood, AK, about thirty miles southeast of Anchorage on the Seward Highway.
http://www.snowtours.net/
If you want to watch the floatplanes, drive on the road to the airport (International Airport Road) and watch for the Alaska Department of Transportation building - they have a big parking lot that abuts the "runway" for the seaplanes, and I'm fairly certain it's open to the public or that they look the other way (I've been there many times and there are always a bunch of random people hanging out watchcing the seaplanes).
The Anchorage Museum of History and Art is smaller but very nice and can be combined with a visit to the Alaska Native Heritage Center for about $20 per person.
The drive from Anchorage/Girdwood to Seward is amongst the most beautiful in the country, definitely plan on stopping frequently for photo opps if the weather is nice.
If you want to try and get some bear (and other animal) viewing in quickly and easily, the Alaska Wildlife Conservation Center might be an option (I've never stopped, but photos from there always look nice).
http://www.alaskawildlife.org/
And probably completely irrelevant, but my two favorite stops in the Anchorage Mall are the Iditarod Store (near the C street entrance) and the Fruitland smoothie place on the food court level - their tea smoothies are very good...
Final piece of advice regarding Alaska - you'll never see it all no matter how much time you spend up there, so plan on coming back frequently and you'll never be disappointed with what you "missed" on a previous trip. It's a truly amazing, beautiful and rugged state.
Have a great trip!
Sean