So here's what the weather breakdown appears.
For Muskegon- I get there Saturday, probably between noon and 2 pm. I might get some time in Lake Michigan that day, but it'll have to be before dinner-ish. Sunday looks to be practically spring-like weather. The cooler weather does favor the 2 wood coasters there at least. I was contemplating the water park, but not with those temps.
For Port Clinton and CP, Monday looks to be ideal for exploring Port Clinton and maybe downtown Sandusky a bit. Does a look a tad too cool for Lake Erie swimming. Tuesday looks gorgeous for Cedar Point (expecting some crowds, but Tuesdays are the best days to go for most parks). Wednesday starts good, but I may have to get lucky for night rides then as rain appears to be arriving later. It appears far less humid than it initially appeared.
This is meant to be a very lax trip compared to my Missouri trip later in July, so for MIA and at least one of the CP days, I'll be taking my time.