getawaytoday.com has up to 8 day hopper passes and their prices are unbelieveable, with service to match. I always pay for them either over the internet or call them and they will send you a confirmation to your email address, and also an additional confirmation slip in your home post mail. All you do is take either confirmation (Either one printed from your email, or from your home post mail) Bring it to the park and they give you your tickets right at the gate. Its all electronically done.
I only deal with Getaway because its just so much cheaper then anywhere else I have found.