Boy, do I know this one!
When I'm going out to eat in my home town, I usually pick the restaurant because I know they have a specific dish that I want at that particular time. My friends tease me about always ordering the same thing at any given restaurant. As someone else commented, if I try something different, I'm usually disappointed.
When traveling, I also love the roadside diners. They always have things like hamburgers, fried chicken, meatloaf, and chicken-friend steak, and those are usually their specialities, so they're GOOD. If I can't find a diner, my next choice would be a burger joint (preferably not a chain), or a Chinese place (I always order General Tso's chicken or orange chicken or sesame chicken - haven't found a Chinese restaurant yet that doesn't serve at least one of those).
Oddly, I love sushi, and when going to a sushi restaurant for the first time, I'll try all kinds of things. But the ones I go to often, I have already gone through that process, and I order the things I know I like best.
If I end up (for example, at a business lunch) at a place where they have a huge menu, I spend a HUGE amount of time trying to decide. I usually narrow it down to two or three dishes, but then I have a really hard time picking just one. I like the idea of just going with the first thing that I come across that appeals to me. But then I will feel obliged to start at opposite ends of the menu each time I find myself in that situation.