Have you tried any of the calibration DVD's like Digital Essentials or Avia? Sony makes a great display and I've heard the outboard scalers are very good, so I wonder if there might need to be some adjustment. 70" and outboard scalers are out of my comfort zone though. Maybe Sir T will step up here later.

Do you know the "native resolution" of your TV? My 62" DLP says it's 1080i, I experimented with switching from 720p to 1080i out of my bd-p1200 and noticed the 1080i was much better. Even on a down hill ski sceen where Progressive Scan is said to have an advantage. So don't go against the "native rez". Knowing you I'm sure you already have fine cables. Hopefully you also understand there can be gain from using good power conditioning products. Do you sit at or close to the recommended distance from the screen? Other than that I'm out of ideas. Most places have a 30 day return policy, pop in and pick up a BR player and give it a spin. Some will include a movie in the box.