Yeah, my wife and I always have to remember to split an entree at US restaurants. Once we split an appetizer, and, not having been that hungry in the first place, were basically good for the evening.
Well I can name one place where portions are exactly the right size and it's McDonald's. E.g., cheeseburger plus the Caesar salad w/o chicken, plus french fries plus two apple pies plus a coke is about half the size of a meal in a regular restaurant. Which of course doesn't stop people like my girlfriend from bashing McDonald's as non-healthy and preferring places where "gourmet" burgers range from 1/3 to 1lb, i.e., the smallest one is bigger than the quarter-pounder.
I don't think McDonalds is as bad as some people make it out to be, but it's not all that great either. You're not getting high quality food there, and in terms of a "dining experience", the ambiance leaves something to be desired:-)
Not to single out McDonalds...I went to Wendy's the other day and got a medium (i.e. smallest) combo meal. The "medium" drink I was given was a 32oz cup. If it were a HFCS drink, it probably would have been just as many calories as the food itself.
The food quality/quantity is a secondary concern if you're doubling them with a sugary beverage.