If you buy the flash pass. I recommend skipping the water park so you can make the most use of your flash pass. If you don't get the flash pass, it would be very difficult or impossible to do all the major coasters and the water park in one day. Wait times for major coasters will be about an hour, probably more for Goliath and v2 (I recommend skipping V2 as it's a low-capacity ride with a slow moving line). Weather is really the #1 factor you have to be concerned with. If the weather is nice, or even decent, the park will be packed. If the weather is cold and rainy, you may be able to ride most coasters with very little or no wait. Of course, get there early as possible to make the most of your time.