Awhile back I messed around making an arms race map based around the central staircase of a cruise ship. Couldn't get to the topside though.. just looking out the windows. I stopped working on it and abandoned it, after wasting time modeling columns, balcony rails, and a grand piano, though ><
The ship I was basing it off of was multi-leveled as well but I blocked off one of the levels so players only had access to two.
Three levels could be a bit much But anyway, just your brushwork alone is making it already look pretty nice. Can't wait until it's fine-tuned and the models and textures get applied!