Carla G wrote:(Trying to think of things not easily seen/ had in GB. )
Try getting injured or sick. Then he can see what a medical bill looks like. Probably works as well for Carla's Brit guest or Linda's Irish one.
Mammoth Cave is a good idea. If they are into cars, maybe a trip up to Auburn, IN for the Auburn-Cord-Duesenberg Museum is in order. Serious as a heart attack, this is on another level. Look it up. How about a bourbon trail tour? With respect to the folks who brought whisky distilling over here, we really, really have taken it up a couple of notches over both the Irish & Scots [Carla, for your English SIL, 'Scot-land' is the terra incognita north of Hadrian's Wall. At least one route of safe passage they call the "M6". My wife & I know because we took it from England & back & lived to tell the tale]. On the Bourbon Trail drive you might even happen across some folks selling fresh made sorghum by the roadside. And if he spots a 1968 Mercury Cougar moldering in a barn, he just might buy it to restore. You can do all this & likely never encounter a roundabout. Or while he is here, he can start his own business - then we've got him for life! Mixed bag, America. Most of these experiences are worth trying before going back to the islands.
Have these two guys had grits or sweet tea? We are kind of on the northern borderline of both of those culinary peculiarities & I don't really get either one. Just wondering what they make of them. Or cornbread, now that's a really good regional food. Just eating it outright, dipping it in milk first is just for regional historical re-entactors, like pouring boiling coffee onto a saucer & sipping it off.
What do they make of restaurant tipping? Groceries with staff who bag your purchases (OK, maybe they do that in Ireland, not sure)? Or prices that aren't really the price? Petrol is pretty much the only retail purchase we make here where the price really IS the price. Or the attention we give to a new royal baby or royal wedding more than two centuries after cutting the cord like some creepy ex who follows your every move on Facebook? And we broke up with them! So now we get all sentimental with the UK and frosty with our old friend France, after they supported us during the breakup ["The English abused you. You deserve better"]. Poor France, a classic example of what happens when you badmouth your buddy's ex and then they end up having a better relationship later on.