The USS Iowa museum is open 7 days a week from 10a-4p. There is a 2 hour self guided tour that can be purchased for $26 pp. You can buy the pass in advance or as a walk-up
https://pacificbattleship.com/museum_visit/
As an add-on to the $26 general access ticket (that allows you to do the self guided tour), you can purchase online a private guided tour for $75 pp (additional). It runs daily at 10:30a, 12:30p, and 2:30p.
There are other add-ons, too. Some require 2 weeks advance notice (the Gun Tour).