FOLLOW UP - Chirp/squeak from rear suspension - any suggestions?

[Boston X5 4.4]

Yes, I seem to have the dreaded rear suspension chirp. When it happens it is loud and sounds like a bird is being tortured back there. I have done some searching on this and seems to be a fairly common issue.
Problem is that it seems that it could be any number of causes. So far I have seen the following suggestions...
- rear upper or lower control arm and/or ball joint (most common)
- CV joint
- coil spring base/supports
- carrier bushings
- handbrake cable

So, before I just replace the rear ball joint/control arms I was hoping that someone might be able to shed some additional light on this based on my specific symtoms:

- Seems to be coming from drivers rear side
- Periodic. It doesn't happen every day but seems to be getting more frequent.
- Rotational - what I mean is that it is not a constant chirp when it does occur but as I increase speed the frequency of the chirping increases. Made me think that maybe something was rubbing against the wheel (calipers look fine)
- Seems to be independant of braking other than gets worse when slowing down
- Worse at slower speeds
- Worse when turning but also happens to a lesser extent when going straight. I can pretty much always hear it when turning left in the parking garage.
- Doesn't seem to be any worse when going over bumps.


Thanks