Yes on the Moose. Also always crowded, they are printing money. Decent beer, too.
Back to the OP question, I lived in Anc 3 years in the 80's. Saw the lights twice during that time. So setting the goal as seeing the lights, within a one week period, looks kind of unrealistic.
As Mac and others have said, there is a great variety of things to do and see. Getting a plan organized is a good idea. Just arriving and driving may not work well.
The inside passage cruises and their excursions are a pretty good entre to SE Alaska (Juneau, Ketchikan, etc), if cruises are your thing. Guided fishing on the Kenai peninsula, or out of Homer, is great. I go with 3 other guys to fish out of Homer a couple of days, then about 5 days on the Kenai for sockeye. We bring back about 100# of filet per man. If the day is decent, that is, the seas don't scare the shit out of you, then being on a 28 ft boat in Gulf of Alaska beyond the Barren Islands is like some scene from a science fiction novel. Some alternative planet. Just incredible.