Do you do HHN? I don't, so that's my reason for sticking to Preffered. If you'll use the ticket, and really like the Valet, I'd stick with Premier.
With regards to the 3rd park, I'd personally hold on adding it to my AP. You'll be blocked out for July coming up soon anyway, and give it some time for the crowds to figure it out and them figure out any Tapu Tapu issues. That's JMO though.