Since you're going in what is pretty much the busiest time of the season -- you're going to have to wait in lines. They won't be too long, but you'll probably have a 45 minute wait for the Great Bear after 12:00pm.
Get to the park at 9:30am.
When the gates open, run to the Comet. Ride that and the go over to the sooperdooperlooper. You should be able to walk right on that. Head up the hill to the Great Bear. The line won't be longer than 15 minutes. Next, headed all the wait out to the other end of the park. It should now be about 11:00am.
Get on the Wildcat and then the Wildmouse. Next, ride the Lightning Racer.
After you've done all that, you've ridden every major coaster in Hersheypark and it's not even noon yet! Go ride anything else, but you will have lines. After 8:00pm, the lines should be gone.
Longest line in the park will be the Wildcat right around 3:00pm. It will be 1 hour 30 minutes approx.
Best place to eat:
Food court in front of Sidewinder.
or
The Minetown vittles cafeteria -- it's inside and air conditioned.