Does your room have to be long or wide?

[papomaster]

Hey all!

I'm planning to put some better speakers in my room, but it has a strange topology :

11 feet wide, 18 feet long (including a small hallway of 2,5 feet surrounded by 2 wall-surrounded wardrobes) and about 9 feet tall. Right now, it is a bit crowded with a 11-feet long desk, a double bed, a lazyboy beside my headphone rig and a stringing machine:

Needless to say, it isn't in the perfect situation to put some expensive speakers in there right now. However, I'm planning to move out some stuff and re-arranging the space to leave a big empty spot in the middle of the room to get a good listening space for speakers (as I'm moving while I listen to music out of speakers in my room).
I would let some room for speakers to stand as well (floorstanders or bookshelves), but I want enough power to fill up the room quite well, as this is the only thing I can't have with headphones right now (would take some dough, though).

Should I re-arrange my stuff in order to make my room 15' wide by 11' long or 15' long by 11' wide (with stuff surrounding the listening area as well)?

 

[bigshot]

The longer the room, the lower the frequencies that can be reproduced without bouncing off the walls. The closed in sides will probably cause problems too, but you can deal with that easier.

See ya
Steve