I finally settled on a pattern for the 3 balls of Southwest Trading Company Oasis that I bought almost 2 years ago... the Aleita Shell from Interweave Knits.
To prevent pooling, I used all 3 balls of yarn for the stockinette stitch portion of the shell and alternated strands every row. I'm alternating between 2 balls every other row for the ribbed portion. I'm making this on US4 and US5 needles instead of US3 and US6 so that I get the correct gauge. I've heard that this yarn stretches a lot, so I'm making it with more negative ease than I usually do. I made a swatch and found that the yarn does indeed stretch after blocking. I tried it on last night and found that it is a bit small now, hopefully ::crosses fingers:: it will fit perfectly after blocking. I'm also making it 2 inches longer than what's called for in the pattern.