Just had to chime in and say that my sister lives in Adelaide! It's a Small World! (pun intended!)She just came back to the states for a visit in April/May. We spent 2 days at Magic Kingdom and it was amazing. Just to really soak up the atmosphere and be together in a place we could only dream about when we were children was worth more than I can tell you. I realize you are traveling with friends, but Disney has hooked many a "non fan" and kept them coming back for life! You may someday have a family of your own... this is the type of place you will long to share with them.
My 2 cents, you can ride a rollercoaster at any regional Theme Park. While they offer an adrenaline rush, there is no lasting impact. My husband is a big tattooed/ pierced guy, not your typical sentimental type, but for a few days he was a kid again. There was an indescribable feeling of something we lack on an every day basis. Joy, wonder and lightheartedness. We would go again (even without kids!) no doubt.