We have 4 teens between 13yrs and 15yrs of age. Universal was perfect for their thrill-seeking independent selves. We bought the 7 day pass, good for both Islands of Adventure and Universal, even though we were there for only 3.5 days - it was same price as two-day and gave us flexibility and feeling we didn't need to rush.
We also had early 8am entry before its open to the public. This was worth it - Run to Harry Potter Journey ride to avoid 80 minute wait lines! Most days lines opened up 1.5 hrs before close. Pay attention to open/close times on their schedule/website as they do vary. Oh many rides won't even let you bring a backpack into the waiting line. Lockers are available but fill up fast closer to the rides. So either leave at home or get first thing at guest services.
Best rides at Islands of Adventure- #1 Harry Potter area - journey ride and Dragons Challenge coaster. This whole area felt like a movie set and very crowded. Had unique foods and drinks.
#2 & #3 tied for hulk coaster and Spider-Man 4D
At Universal - #1 & #2 tied between the Rip Ride Rock it coaster (each person has their own sound system and gets to pick own song for the ride. Wide variety from Rap, Country, Rock, etc). And the Mummy Returns 4D ride was an unexpected spectacular effects.
Skip: Twister and Men in Black - very dated. Shriek 4D was entertaining but a stationary and mild experience. If you do this before the other 3/4D rides your expectation may be better or if your feet are tired.
Eating - we ate at CityWalk at the Latin Quarter. REALLY good food and portions - share and save calories and $ and still taste great. Most restaurants required reservations but they did have a food court with Moe's and Panda Express and BK. cityWalk is OUTSIDE the entrances of the gates to both Islands and Universal. Was easy to walk between all three.
We went mornings and evenings. Swam at the pool at our hotel midday.
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