About a 130" diagonal screen would be max I think - Just under 10 feet wide. I would put eye distance from the front row at screen width (8 to 10 feet, whatever you end up with with for screen width). To me, any closer is just too close. A 130" screen takes a powerful projector.
Maybe look at the new epson 5030ub. I'm not sure what your budget is for the PJ but for around 2500 bucks its suppose to be one of the brightest and best picutures out. This model just came out to replace the 5020ub wich from what I hear was a light cannon. I guess for the price range the 5030ub also is suppose to be great for 3d in it's price range. There is a big thread over in the PJ forum about it. That's what I'm leaning towards when I finally am ready to buy one. Hopefully this summer.