Definitely add some (local) crayfish BUT let them establish before the predators are added. I like the looks of Pumpkinseed sunfish versus Bluegill and yellow perch are nice. One note on your wish for Pike. Yes, they will eat everything in site but are cool to have - I love their looks and they are a great ambush predator. Instead, consider chain pickerel which are in the same pike family and don't get nearly as big. Grass or redfin pickerel are too small and will get eaten by bass, etc. but Chain pickerel will hold their own. Unlike Pike, who will eat everything out of house and home, chain pickerel (so I hear) will keep a decent pond balance and prevent both Bass and sunfish from getting overpopulated as they will eat some of the 6-9 inch bass. Any pike species likes some weeds or lily pad areas to spawn in and to ambush their prey from. This is one way to control them. i.e. of you have minimal weedy areas, the pickerel will never get out of control. Not many people sell chain pickerel, but you should be able to catch them from other lakes in PA.
