there were about 20 people at saddlebrook when we were there, they described it as a very light week. There was little to no socializing with the people on other courts after tennis.
At newks, it's almost impossible not to socialize after tennis. There is a central pub with music, contests, etc. Given your criteria, I'd head to nukes... One of the key differences is that saddbrook is a destination resort while nukes is close enough to austin to draw a big local crowd. I'd call sooner rather than later as they may book up that week.
hope you'll report back with your experience.