Before you start talking about bass traps you have to know what the acoustic properties of the room are. Why not hop on over to Audio Theory and check some of the older threads on how to measure this (you need a PC, microphone and preamp (RS SPL meter works for this) with tripod, a duplex (record and playback) sound card, measurement software, and some cables).
Rattles you can eliminate by playing the sub, finding, and eliminating them. You can also get a general idea of your overall frequency response by playing the Avia (calibration DVD) sweep tones.
No matter where you go. ... There you are.