Paella and calamari are both hard for me to pass up.

Jamaican oxtails
Osso Bucco

Answering for Mrs. Yuengling, if we are anywhere and there is Thai calimari or chili sauce calimari, I know that we will be getting it.

My "must orders" are usually specific to a venue type, as I try to have the same dish at multiple places for comparison purposes. For any new restaurant...
Thai: Panang Curry
Vietnamese: Barbeque pork Bahn Mi
Italian: Something with Arrabiata sauce
Mexican: Guacamole
Chinese: Eggplant
Dessert: Tiramisu

Tuna steak (black and blue)
Coq au vin
Filet mignon, medium rare, with a wine sauce
Croquetas de pollo (Cuban style chicken croquettes) with a spicy red sauce


So, nothing fancy. I'm all about comfort foods.

ETA: Wait. There's one other thing that I cannot resist, when it's in season, in a restaurant that takes quality seriously: truffles.

Gnocchi.

I rarely see this on menus (obviously it's typically at an Italian restaurant), but when I do I typically always go for it. I haven't been disappointed yet.

A fancy grilled cheese. If I'm at a casual restaurant and they have some sort of interesting grilled cheese, I'm all over it.

I'm a sucker for meatballs. Doesn't matter to me what type of restaurant it is, but I'll always get an order or two for the table when they are listed as an appetizer.

I typically like to change it up as much as possible. The only things I can think of are pork belly and flourless chocolate cake.

Chirashi

Beef tongue

Oxtails

Short ribs

Lamb or pork shanks

It's rare to see it on a menu, but if an Italian restaurant has pasta with finocchio (fresh fennel), I am going to get it. Inevitably, waiters ask me if I'm sure and, yes, I am in.

At Jewish delis, I have to get a tongue sandwich. And full sour pickles. And a kasha knish.

There are several other dishes I order frequently, but don't consider must haves. Beet salad and seared ahi are two that come to mind.

For desserts, it's very definitely seasonal. In summer, you can't do better than fresh berries with grand marnier. In winter, I eat chocolate desserts. Or poached pears.

For breakfast, I'm most likely to get an attempt at a Mexican / southwest omelet, i.e. something with salsa and cheese. Unless I am in Asia, in which case I cannot resist getting noodle soup for breakfast.

This particularly inspired me to have a raclette, pear and rosti dinner yesterday. I still feel a bit bloated!

I thought of another one: mussels, and that is one I stick to without fail.

I love Key Lime pie, but nobody makes it better than I do. :o And, surprisingly, it is really easy to make. So, if I see it on the menu, I'll ask the server what he/she thinks about it. Because when it's not good, it is really disappointing. It can't be served with anything other than real whipped cream.

At a Mexican restaurant, it's hard not to order carne asada. Similarly, at an Argentine restaurant, it's hard not to order entraña (skirt steak).

I'm also a sucker for chicken parmesan at an Italian restaurant. Again, I always ask the server's opinion.

Same at a Brazilian Churrascaria. Frauldinha is the best. (Sorry picanha lovers):)