Check out the Personal Navigators from previous 5-night cruises for your ship.
http://disneycruiselineblog.com/personal-navigators/
While your particular cruise will not exactly match a previous cruise, it can give you an idea of what characters are available at what times of day.
Also, I found that I'd see most characters on our Disney Wonder 5-night within 10-15 minutes, depending on what time I got in line. Definitely book your free tickets for the Princess Group and for Anna/Elsa as soon as your booking window opens. We saw 4 princesses in less than 5 minutes and Anna/Elsa we showed up five minutes early to find that they had also started early, and there were only 3 people in line ahead of us. Pirate Mickey on Pirate night was more crazy. We had to wait 20-30 minutes for big ones like that.
Another thing to keep in mind is that if you do the 'Til We Meet Again show at the very end, all of those characters (Fab 5, Princesses, Chip/Dale, Stitch, Captain Hook, even the theatre show cast) will mingle around for about 15-20 minutes. We got like 6-7 characters in barely 10 minutes that way.