June 16th, ehe?
Well, June tends to be a busier time, so you will probably need a good day and a half to get all the coasters, counting a few re-rides on your favorites.
I would recommend skipping soak city, unless you are partial to water rides.
Challenge Park, just like Soak City, is an area full of up-charge attractions. I would recommend going on the Ripcord if you've got the money, but skipping the rest of it also.
The entire trip would depend on how you're getting there, how far you are, ect. If you're in the tri-state area, I would designate 3 days, counting driving, plan for the worst, and hope for the best.
Must-rides include the Millennium Force, Magnum, Raptor, Blue Streak, Gemini (Yes, both sides), Power Tower (Both sides on that too), Demon Drop, and Mean Streak. Then head for Disaster Transport, Draggin' Iron, Corkscrew, Wild Cat, Woodstock's Express, and Mantis if you've got the time. You'll probably want to get on Mine Ride, just because, and you may want to borrow someone's kid to get on Jr. Gemini, just for the count.
Make sure to eat some Dippin' Dots, buy some cheesy souveiners, and toss back a cold one at Red Garter, if you're of age of course. Oh yeah, and HAVE FUN! :)
Hope that helps...
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"Johnny Rotten shot me with his BB-gun."