Some notes from my trip to Michigan...Do NOT go to a Wendy's. Like McDonalds, only worse!
Wines (at least in MI) were all very expensive. A bottle of cheap plonk was about $6-7, and anything halfway decent (like you'd pay £4 for in Tesco) was at least $8-10. The beer is mostly pretty good - you can get decent lagers everywhere (if you pay a little more for your pint), and there's pubs which specialise in "real beer" and usually brew their own, where you can get some decent stouts and bitters (the word is "brewpub").
In pubs, the moment you put down an empty glass, expect the waitress to ask you if you want another (or just appear with another full one!). Pub service is generally quicker than in England. If you order a soft drink with a meal, you'll generally get as many refills as you need. And if the meal was large, it's quite normal to ask for a box for the leftovers, to warm up and eat later.
There's no proper chocolate over there (unless you find some specialist shop). Snickers and some other bars are made over there, but they use Hershey chocolate which is just sugary sh*t with no real taste. Certainly you can't go into a newsagents or supermarket and get a bar of decent chocolate.
Everything has extra sugar, so brush your teeth well.
Nearly all bread is sweetened, either with sugar or some variety of sugar syrup, which makes it taste strange - not bad, just different. You'll have to search hard to find wholemeal bread, even in health food shops.
Food in stores comes in ridiculously large quantities. I had problems finding milk in 2-pint quantities rather than 4-pint or 1-gallon! All jars of spreads are huge.
Milk doesn't come in whole-milk, semi-skimmed and skimmed, but has some high/low fat content percentage on it which I never figured out.
In shops, Americans expect to have their groceries packed in carrier bags for them. You get amused looks if you do it yourself (as most ppl do in Britain) - you also get some appreciation from the shop assistants! All checkout assistants I met were friendly, although I guess having a novel accent can help. It may just be where I went, but the queues seemed longer for grocery stores than you'd expect in England, and the assistants didn't serve nearly as quickly so the queues moved slower.
Credit card signatures are never checked - the procedure is usually to swipe the card yourself in the machine on the counter (check the machine to find which way the card goes), keep hold of your card, sign the receipt and give the signed copy back to the assistant. The assistant doesn't take the card off you to check the signature.
That's all I can remember offhand. Those are the main differences I noticed relating to food. I'm sure most Americans will look at the list and say "Well yeah, how else would you do it?", but it's surprising how strange it is not to be able to get normal things like wholemeal bread and semi-skimmed milk.
Oh, and don't forget, everyone's almost unnaturally friendly. It does seem like Stepford sometimes, but it's very endearing. Whilst I don't agree with a lot of American traits in particular (huge cars, sugary food, no pedestrian access, guns), I do like the people in general. It's a refreshing change from "I'm-alright-Jack".
Graham.