One thing I will say is that the USA fast food breakfasts are FAR bigger and with more variety. Subway, for example has a full range of egg white omelette flatbreads and whatnot. Over here it's like an afterthought, taking the standard bread and shoving a sausage in it.
If you're hungry, a McDonalds Big Breakfast really IS big for me; consisting of scrambled egg, sausage patty, English muffin and hash brown:
But the US version has an English Muffin, Buttermilk Biscuit, two pancakes with jam and syrup, streaky bacon, sausage patty, scrambled eggs and a hash brown (phew!)