From 8-12 feet away, don't get anything less than 47" or you'll be extremely sorry. 55" would be ideal at that distance.
If you're sitting opposite a window, the 3SV is the far better choice since it has a semi-matte/diffused screen which negates reflections. To add, the 3SV is an amazing performer and its price makes it a tremendous value, thus its scarce supply.
Current: Sharp Elite PRO-70X, Panasonic ZT65, Samsung PN64F8500, Pioneer Elite Kuro PRO-151FD 60"
Previous: Sony XBR8, Sony XBR4, Sony WEGA (various)