Complete American Fort I

Small little nitpick, I know other players feel this way as well:

Grass, flowers, and similar terrain enhancers should be used sparingly. CTF is a game centralized around PvP, and a game in which you cannot break most blocks. This includes grass and flowers. They definitely make the map look amazing, but it really does get in the way, especially when you can't remove them by hitting them (hence why I mentioned being unable to break blocks).

Easy example, because it's right there: in the last screenshot, imagine you're playing on the slabs inside the tunnel. It would be extremely difficult to hit someone who is standing right on the outside of the tunnel, where the grass is. Maybe they might not be able to reach you from where they are, but a lot of the time, the other person won't particularly mind that. Mage, chemist, elf, engineer, and archer all come to mind in that regard. Also, because of the objective-based gameplay of CTF, it's all too easy to ignore someone and just capture the flag, especially if that person can't hit you because you're standing behind a block like grass. If you're playing medic with the purpose of healing, or soldier or elf with the purpose of capturing, you can take advantage of a lot of this terrain by avoiding combat entirely.

If you take a look at a lot of maps in rotation that use these kinds of semi-tangible terrain blocks, you might notice that the blocks are used very sparingly; there is overwhelmingly more open space than there is grass covered in a block. This is no doubt due in part to the interference with PvP.

If you want to add detail to a build, I'd recommend more than anything increasing the variety of blocks with which you build structures. It can add texture variety on top of being less obtrusive to gameplay. If it matches your style, you can even use open space to create a different aesthetic. @ItalianPenguin is a map maker who I notice uses simplicity and open space to its fullest, while also trying not to allow too much space for classes like archer or mage.