I'll give you the easy one...... East Harbor. It is big and people can spread out, it would be tough to put a dent in the population up there, but all of us ice fisherman try when the cold weather allows. West Harbor can be good too. Find spots where weed beds meet up with break walls or over hanging brush on overgrown shoreline. I know some guys who have spots on Sandusky Bay and they do really good on bluegill there as well.
After that, sorry but you really have to get out and do your leg work here in NW-OH. Lots of the bigger upground reservoirs have decent size bluegill but it can be tough to pinpoint them. They tend to stack up in relatively small areas so if you find them, make mental notes. Sometimes it is just a matter of knowing when and where they will bite at the big upgrounds. Try at dusk and way up high in the water column out over deep water. The crappie schools move up high over deep water in them too. You could spend 5 hours mid day and not get a bite but then it turns into a fire drill for the last hour of light. There are so many smaller reservoirs i could list but those places get hurt quick when people post specific locations on the internet.
My last bit of advice...... use either maggots or wax worms as bait. Night crawlers and red worms definitely work but i have much better success with grubs.