If you're going to fish, PI Bay is probably the best place to go unless you are bringing or have access to a boat of sufficient seaworthiness to go out on the lake.
There is good panfishing and LM Bass fishing in the Bay. This time of year though, the inner Lagoons (north of the road that loops around the peninsula) and the far west end of the Bay (from a little west of the Erie Yacht Club to the head of the Bay) tend to stagnate some and the fishing drops off. Basically, in high Summer, the farther you are from the main Bay, the poorer the fishing becomes. But if you stay more or less in the open bay or in coves with good wind-driven water recharge and fish along the reed beds, there are lots of nice bluegill, some crappie and reasonably decent size perch. These same places also have lots of largemouth. For numbers of decent size bass, the Bay is probably as good as anything in PA.
An alternate, if there is a lot of wind and the bay becomes difficult as is sometimes the case, , are some of the inland lakes a half hour or so south of the city. Edinboro Lake and Lake LeBoeuf have very good crappie fishing and decent bluegill (very good in Edinboro Lake) and perch fishing and also decent bass and pike fishing. Some muskies too, but frankly, for Muskies in these lakes, you should have been there in 1958.
I grew up on LeBoeuf and there used to be a boat rental place. Same with Edinboro. I don't know about either now. LeBoeuf has a minimum wake reg for boats. Edinboro, unfortunately is unlimited HP/wake and is lousy with half wits in jet boats and on water skis. Still fishes well, though. Both lakes have PFBC launches.
There is very, very ,imited shore fishing in both lakes. I wouldn't bother with them unless you have a watercraft to use.
That's a few options, anyway..