FYI -- any topic dealing with impending visits to parks / coasters belongs in the "Trip Tips" section (you're asking for tips, after all).
As for lines in early July, actually, they'll be pretty rough. Cedar Point gets very hectic beginning right around the fourth and continuing into late August -- if you can bump the trip up to the last week of June, the crowds would be significantly lighter. As for lines, some of the coasters will have less than a 15 minute wait, others will be upwards of 45 minutes, depending on the time of day you try to ride them. For the best effect, you'd want to head for Raptor or Millennium Force first, then try Wicked Twister, Magnum, Mantis... Blue Streak, Mine Ride, Iron Dragon, and Corkscrew can all wait until later as they'll have shorter lines throughout the day, though you may want to opt for an early lap on the WildCat since it loads very slowly -- what looks like a short line can take a very long time.
Have fun!