Labor Day weekend will most likely be packed. Good luck.
First of all, I just want to point out that CP is closed on week days after Labor Day. So don't delay!
The first time we went this summer, we stayed from a Sunday to a Tuesday in early July. This past time we stayed from Thursday til Saturday. Whereas Thursday and Friday were downright perfect (most of the vacationers are getting kids ready for school) today was PACKED! If you do go on Labor Day weekend, I would highly recommend looking in to staying at one of the CP property hotels/resorts. They offer excellent packages, and you can even get great coupons online. For instance, we got $15 off of each of our Funday tickets for today with coupons we printed from their web site.
Another reason I recommend staying at the CP properties is because of the parking passes for GREAT parking and the free pass to get in and ride some of the rides an hour early. It is faster to get in and if you park over by the water park, you can come in the entrance that is closest to Top Thrill Dragster--the entrance that goes right under the Magnum. We came in that way this morning and managed to get on the seventh or eighth train out, front row. (It was our fourth time on TTD, but it was absolutely AWESOME, nonetheless!) However, being a weekend morning, the line filled up quite quickly, and by the time we got off it was up to nearly a two hour wait.
I have no idea what the weather forecast is, but I would strongly urge you to take an umbrella just in case, especially with the hurricane down south pushing precipitation north. We got caught in a downpour, and it was chaos!
And...they absolutely will not run TTD in any rain whatsoever, whether it is a sprinkle or a shower.
Another perk to the parking by the water park is that it is so close it is really feasible to make trips to your vehicle if you want to take a cooler with your own food, drinks, etc.
Have a great time...like the guy said when we were on the Rip Cord ride..."Because the Ohio State Law says you have to have fun!"