Car rental will be your biggest surprise expense. When I booked for Anchorage last year for this coming June, the cost was $125/week including all taxes/fees for an economy car. Apparently this is a "mistake" but it is a "mistake" that has happened every year for the past 5 years. Rates now are $300/week or more.
John
John,
FYI - Surprise is an understatement for car rental. More like shock. $550-$650/week is what they are quoting now for full size cars.
Still in the planning stage and waiting to see who is going.