Indoor
I say that because I am building a game that uses the whole map for an outdoor level, and it is really easy to get to the file size limit for the level.
(..like The Storyteller 01 said too...)
So, if you are going to do an outdoor level, then I suggest making it modest in size so you can have some space left for other assets, like enemies.
You could always make alot of alleys between buildings for an indoor/outdoor level to mix it up.
Imagine a catwalk window fron window at say 10 stories high... make it flimsy like a board and then shake it as they go across. (don't faaaaaalllllllll)
I guess the map could be the worst enemy after all.
