There are 2 types of sebae, H.crispa, by far most common, get very large, very light needy.
The 2nd is H.malu, they stay low at sand bed, 8-10" max, very bright colors, one of my favorite for mixed reef, easy to control and keep from coral on rockwork, and they are not so needy for light as crispa.
I have had Malu many times w/ many types of clowns both natural and non natural host matches and every clown I had accepted malu pretty quickly.
Most all other host nems get about 18"-24", some even bigger
I prefer magnifica personally, they stay perched on highest rock as long as they don't touch glass normally, and mine could actually shift to glass maybe if it wanted, but it's getting plenty of light so it stays put, and are natural host to my percs
This is in my 120g no problem.
I could easily have a malu as well, or LTA at bottom, and I think about it, but not sure if I want my clowns bouncing around nems, kinda like them in their mag
You should always consider what type of clowns you have in deciding nems, hosting happens much faster in a natural match as what would be found in wild.