Out of Whitier the 29 Glacier Cruise is a good day trip. From Seward Major Marine's Kenai Fords National Park Cruise turned up otters, humpback whales, puffins, porpoise, orcas, the Holgate Glacier, (which was actively calving), Aialik And Pedersen Glaciers, and that was just the first half of the day!
The Swiftwater Seafood Cafe has really good fish & chips in Whitier.
On the Seward Highway between Anchorage and Whittier is The Alaska Wildlife Conservation Center, which is definitely worth a visit.
Ditto on the tour coupon book. It will pay for itself the second time you use it.
My only other advice is to not wait, GO NEXT YEAR, we are!