It's impossible to see all, do all, and visit all - even in a ifetime.
hikerbum
This is the real truth. We have done 2 cruises and 2 CruiseTours and still feel we haven't seen much of Alaska.
Some of the highlights have been the train ride from Fairbanks to Seward with an overnight stop in Denali National Park. Glacier Bay National Park and Kenai Fjords National Park by boat were great. Sawyer Glacier was also an awesome sight. One of my favorite cities in Alaska is Sitka and you won't drive there as is the case with Juneau and Ketchikan. So, traveling by boat or ferry surely has its place. It boils down to deciding what you really want to see most.
But probably the best part of those trips were getting to know some of the folks on here. If you do go to Fairbanks be sure and look up Mr. 2legit2quit.
Our time with him and his lovely wife were one of the highlights of all our times in the state.
Hope you make it happen because I know you will enjoy it.
