Buddha, you get to shoot the actual tourney? That's great!
I've gone to the (free) Tuesday practice round of the Shell Houston Open the past couple of years, and I've found that 200mm - 300mm is really what you need. Since it was an early practice round, I could get closer and sometimes use a little wider lenses, but unless you're "inside the ropes", you'll need the reach.
Another thing I'll suggest is to try the 21fps burst mode on a few swings, especially with a high shutter speed and at ground level with the ball. You might get some great impact shots.
This was with the DA*200 and the K20D:
This was with the SMC300 and the K100D:
Here are the links to both sets:
2007 SHO 2008 SHO
And here's a set (from a golf outing) showing the 21fps burst mode on golf swings:
21fps burst mode