We stayed in Anchorage, so everything we did was within about 1-2 hours drive from there. The only thing we did that required a reservation was rafting on the Kenai river. It's about as tame as it gets rapids-wise, but absolutely beautiful.
Portage glacier's worth a trip. You get about an hour's boat ride on the glacial lake, getting a good view of the glacier's face and a decent chance of witnessing some calving.
Right near Portage is the Big Game park. It's no San Diego Zoo, but you get some real up close views of Alaska's native large animals.
Matanuska Glacier, north of the city, is one where you can get down and walk right on the glacier.
We've got plenty of
visual aids of what we did.