Route 5 or rte 20 will take you in and across from Erie to NY, as mentioned. Presque isle is also accompanied by a nice small amusement park (Waldameer) and a really great nature center (Tom Ridge Envoronmental Center), both admission is free, and each at the neck of Presque Isle. This weekend is North East's (Right before crossing over to NY line) Cherry Festival if you are coming soon. Discover Presque Isle is happening sometime in the next few weekends. There's a great little zoo in Erie and, by the way, several nice quilting shops.
Let us know what your interests are, we can steer you in the direction you want to go.