Rollfast Gran Fondo

Uh, Carmel Indiana.
I've ridden around the flat parts of indiana. Fast, yes. Stinky, lots of pig farms.
Ride Across Indiana is the popular long ranger , Starts July 15. RAIN – Ride Across Indiana – Welcome to RAIN 2017!
160 miles. Too much for my crotch & hands. Pvevailing wind is from the southwest these days. I've done the Hope ride, the 100 km version, on a mountain bike.
Indiana does have a lot of numbered highways with 14' lanes. I don't have a lot of trouble with cars. Even the county roads, the berm is not as high as Kentucky so I don't get thrown off if I ride off the edge to avoid a car, or combine. The farm equipment will be out in September.
If you want to see some scenery, in Indiana, do the Parke county bridge ride in the fall. Or without a sag wagon, any other time. Lots of covered bridges over creeks. There are mom/pop restaurants & ice cream shops in several little towns.

We have no reason to drive to Carmel to roll fast - it is flat from Seymour north to Muncie. Hope is close to me.
If you want ot knock off 100 miles fast, carmell/Indi is a good place. (rollfast) Flat, not much wind this time of year. Winds shouldn't pick up in September, but weather has been weird since global warming changed the patterns last year.
Reason they do RAIN 160 miles in hot July, there is 14 hours of daylight. Not in September
There are some museums and cultural stuff in Noblesville for the wife/partner. There is a reenactor village and a train museum I know of. See indiana.gov for the tourism link. Hope is nowhere's ville, which makes for not much traffic besides cultivators/combines.
I like seeing scenery and tend to stop at covered bridges and things. I'm not the 100 miles grind it out type. Numbers don't mean much to me.
Go ahead, try it.