I don't know where you are in the state and how long of a drive it would be for you, but from a size/quantity perspective for the fly angler, Presque Isle Bay is the best pike water in the state by a considerable margin. The fishing while wading can be really good from shortly after the ice goes out and the fish begin thinking about spawning (usually by late March) until the smallmouth start cutting redds in mid-May. Fish in the 5-6 lb. range are pretty common and actually about average. Then I'd imagine (but do not know) that the fishing picks up again in the Fall for Pike in the bay.
I would imagine that the Allegheny Reservoir has similar fishing if you can find it. It's a big piece of water. But I don't know that either although I do know it has surrendered some of the largest pike taken in PA.
A lot of cool/warm water streams like the Allegheny and French Creek (NW) and others have decent numbers of Pike. The problem with a lot of these places is that the fish are spotty and the best times of the year to target them are also times when flows are considerably higher and fly fishing more difficult. I grew up on French Creek and don't ever remember it being pleasantly fly fishable until close to Memorial Day.
So, I think a lake is the best bet unless you want to catch most of your pike later in the year incidental to catching bass.
When I've targeted them in the Bay or on Lake LeBoeuf or some other small lake, I've done best on big bunny buggers (like 6-7 inches long) in loud colors stripped right along the edges of the weed lines and usually fairly deep. Big Clousers, a Lefty Kreh hackle fly called the Red and White and big salt water streamers like the SeaDucer have also worked for me. Particularly with the bunny bugger which gets waterlogged, you need a pretty powerful rod to cast these flies all day, like a 9' 8wgt or so. Which is another part of the problem with river pike. A lot of them are about the length and girth of an axe handle and don't put much of a bend in an 8 wgt.
But like some of the other guys have said, the best pike times actually overlap some of the best trout time