Thanks for your input, Janet B! Just reading what your wrote makes me feel excited at the idea of going.

I think my fear is that I don't want to pay a pretty expensive fee (for us both) to get there, park tickets, food, etc., only to regret doing it and saying to ourselves, "Ugh, we could have had another day at Disney!".
Yup, we will be at Disney from 9/8 to 9/16. With ADR's scheduled, and EMH, and all, I've planned to fit in a day at Universal on Tuesday, 9/10. I figured that crowds should be low because, (a) it's September and (b) it's a weekday. Given that, if we do go, would you still recommend purchasing Universal's version of "fast pass"? Also, would you recommend their "park hopper", or could we spend the day at IoA and be satisfied?
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Mears RT $38 for us both sounds nicely affordable! Better than I anticipated. Are they reliable? How early in advance should you schedule their transportation? Could we rent a car with the front desk at Disney, for cheaper than $38 for the day?
Sorry-- this is a rookie question....what is CityWalk?