Join Date: May 2012
Location: DCA, lived MCI, SEA/PDX,BUF (born/raised)
Programs: Marriott (Silver/Gold), IHG, Carlson, Best Western, Choice( Gold), AS (MVP), WN, UA
Posts: 8,729
Anchorage would give you the most flexibility if you book the flight then alter plans.
Do you have your heart set on doing xxx?
Are you sure you only want to do 3-4 days and not 7-8 days?
One thing with Seward is you can manage a visit there by train and not need a rental car to drive there. So you go there and back by train then you could rent a car for a day or two to do a few other things.
In terms of season I would look at mid June-midSeptember. Later August it dies down with tourists thus prices likely will drop.