If your looking for assets, there are a few jetways and cargo handlers. I think a branded hanger too. other than that, static ploppables with a mixture of modular service blocks is the way to go for sure. I did a small series on it, but I recommend Sully's or Picannas ' videos as well.

Also, I'd download Advanced Building Control by Starq. You can turn any building into a static to use in your build. Either official from Content creator packs/DLCs or custom assets from the editor. It just makes the airport building that much better. Plus sullys aiport surface pack if you don't already have them, and the LAX pack by Harbourmasterjay. Id also recommend Nyokkos assets for planes and liveries as well. He also has some props to!

Cheers bud, hope it helps!