From Niagara Falls to Cleveland, I would follow I-190 to Buffalo. Get on Buffalo Skyway (route 5) to reach the Coast Guard station there to see the Buffalo Main and other lights in that area. South Buffalo light is about 2-3 miles south along Route 5. I would follow Route 5, also called Lake Shore Drive, south to Dunkirk to see the lighthouse and museum. Then to Barcelona, Erie PA. Continue on 5 until it becomes 20 and then 531 in Ohio to see the Conneaut light and Ashtabula lighthouse. You'll end up back on 20 to get to Fairport Harbor and the lights there. Then you might as well get on I-90 to Cleveland.

If you have the Penrose Guide to Eastern Great Lakes lighthouses, take it as a guide. It's very good.

I cannot help with the other leg of your trip as I haven't been lighthousing on the Gulf of Mexico.