I was there Labor Day last year. The park was packed, second worse I've ever seen it (behind KennyKon 2001).
Kennywood isn't a "small" park, but it's definitely not one you have to go running from coaster to coaster or ride to ride to get it all done. I'm sure you've already figured this out, but there are five adult coasters. Jack Rabbit and Racer never have lines more than 20 minutes. Thunderbolt's can be a little longer than that, but still relatively quick. I'm sure that, as an enthusiast, you know how to look for two-train operation and whatnot, so take that into account when you see the lines.
You won't have to worry about that on Phantom's Revenge, though. They'll be running one train all season. As noted above, the lines can and will get lengthy, so try to hit it early in the morning. Exterminator should be next after PR. It's a relatively new ride ('99) and doesn't have great capacity, so the line gets long for it too. Even on the busier days I've been there, PittFall's line never seems to get all that long. Plus, its queue is shaded.
Definitely take time to eat. Of course, there's always the Potato Patch (I recommend a side of cheese.) I've heard good things about the corn stand, just below PR's lift. Put your own toppings on some corn on the cob. Why didn't they come up with this sooner! ;) The only indoor restaurant in the park is the Parkside Terrace, near the carousel. And grab a corn dog, too.
Good stuff!
Kennywood, as you know, is home to an eclectic mix of flat rides. Aero360 is the newest. It's a great little ride that hopefully will quench your looping thirst for the day, since it and Enterprise are the only upside-down rides in the park. There are a bunch of old flat rides, namely the Kangaroo and Turtle, that might be of interest to you. The Roll-O-Plane won't be open, sorry.
Take a ride on the Olde Kennywood Railroad for a break from the rest of the park. It's a cool, old train that gives you a little bit of history about the park and the surrounding area.
As discussed in another thread, the dark rides are great. Old Mill's line can get a little long at times, as can Noah's Ark's, but Gold Rusher's should be short. Of course, you already know to ride Exterminator.
Hope you have a good time! If I think of any more to say (!), I'll be sure to post it here. ;) Have fun at my home park!
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Matt Lynch
Co-Webmaster, Kennywood Boulevard
http://kennywood.coasterbuzz.com
*** This post was edited by Lynch on 8/12/2001. ***