Some of the screens are still to large.
http://www.snarkpit.net/editing.php?page=tutorials&game=HL2&id=158
Read the tutorial please.
Screen #1: A box with stuff inside.
Screen #2: Nice architecture on the building in center, but its a skybox, with stuff inside.
Screen #3: Another box, yes with stuff inside.
Screen #4: another angle of screen 1. A box with a walkway inside.
Screen #5: A hallway/box with stuff inside.
Don't hand me that "real world" crap. There is some interesting architecture out in the real world. In a game environment where you can literally build the entire map and balance it upon a pin, you do not have to restrict yourself to recreating square rooms with stuff inside.
If you have trouble with your framnerates, you have trouble with your mapping style, not its theme. In other words, you haven't been trained properly yet and Snarkpit specializes in mappers just like you and their improvement.
Anyone can be taught, even you.