Go out with your friends and get roaring drunk - I might be wrong but I think attitudes to drinking are a bit more strict in the US.
If you're going to the Chicago area you'll be fine.
There are beaches in the midwest - the shores of the Great Lakes have some of the best beaches I've ever sunburned on. Michigan in particular has gorgeous, sandy shores. Wisconsin boasts the Door Peninsula, with glorious beaches on both sides.
The historical sites available to Americans are multitudinous and very varied. Just a few examples - the Spanish missions of the SW and California, Pueblo habitations, Saint Augustine in Florida, the Oregon Trail, the entire east coast with its links to slavery/the triangular trade, New England and the earliest Anglo settlement of North America, American Revolutionary sites, battlefields of the Civil War, the Cahokia Mounds, Route 66, older cities of the east and south, and varied/regional architecture everywhere, esp in Chicago, but there are places much older.
Ok, 'It lacks historical sites when compared to the UK'
So much depends on your definition of history.
I'd say public footpaths/ the right to wander would be missed.
Other than that, and historical sites dating from before the 1600s, the US is interesting, even the midwest.
Plus, you can enjoy nice pub grub in many an Irish pub.