I'm kind of in the same boat... My buddy from here on the site (and here locally) goes all the time, and so he's my droid drug mule of sorts. I think a 2-pack any time he's there is so cheap, why not just build another?
One of my new favs in my collection is a white R4 dome, blue body, white legs... The contrasting colors are awesome.
Also I have an all solid blue R2 now, and man, it's a great way to get the R2-D2 dome without having any white there. Very distinctly different from R2-D2... I'm wondering though, a white bodied R2 with solid blue legs may look pretty awesome too.
The color contrasts really can make for some great background droids though. Droid Factory at WDW is really the 2nd coolest thing they've done... The Starspeeder 1000 is still first in my world and I'd buy a repaint (Yellow, please!) of that beast in a heartbeat.