Ryan,
Honestly, I don't think you'd have any regrets going with any of your choices. I've owned a Hitachi 48" and a Sony XBR 61" for 8 and 10 years, respectively. Never had any problems w/either of them. I still believe that the Hitachi I own has the best picture I've ever witnessed shy of HD.
Now, the 65" HD Sony you're considering is an awesome box. I own all Sony equipment, so I'm somewhat partial to this one. The DRC circuitry that this one has built in will allow all 480i SDTV signals to be interpolated up to 960i. This is a very big feature in my book. It will likely carry about a $2,000 price tag just for this feature.
2nd on my list would be the Hitachi. The quality and picture are top notch, however losing 4" of display might bother some that are used to the largest 4:3 screens.
I don't have any personal experience with Pioneer Elite other than every time I see one at an A/V store, I remark that the Elite picture and craftmanship are exceptional. Also, I've heard that Pioneer Elite are all handmade components, which has excellent appeal as well.
Lastly, I've seen the Mitsu on display. I didn't have any problem w/it, however since Mits doesn't make every A/V component out there, I've never really been attrached to this brand.
Hope this helps.