OK, based on your criteria, you have some quality choices for the money you are talking about. You said your viewing area will be 6-8 feet so I'm not sure I would go any bigger than a 65 inch but that is something you will need to go into a store and judge for yourself and your family. I believe the Sony KDL-55W900A is the hands down the best LCD TV made in 2013 and the 55" will be a good size with your 6-8 feet viewing area. Otherwise, a close 2nd is the Samsung UN60F8000. I don't think you can go wrong with either of these sets. The Samsung is a little brighter than the Sony but supposedly doesn't handle reflections as well as the Sony. The Sony has the "Deep Black Panel" which handles glare and reflections very well which will help in your environment. This year I believe the "deep black panel" is only on their highest end 2014 4K set. The Sony KDL-65W850A which you mentioned is an offshoot of the W900A but doesn't have the Deep Black Panel and the 240Hz refresh rate. It is an excellent TV, just not has good as the W900A.
Plasma is an option but I only list one, the Samsung PN60F8500. It is the brightest Plasma out there and has outstanding reviews. The Panasonic Plasma like the TC-P55VT60 is outstanding as well but Panasonic is getting out of the Plasma business and no longer making them. They will be harder to find and the price seems to be around $3,500, out of your budget. The Plasma may not be your ideal set since you have a lot of windows but you'll have to look at the set in person to see if it will work. Vizio is offering a "P" Series LCD TV in August which will offer Full Array Local Dimming (FALD) & 4K but cannot recommend it until the reviews start coming in. Also, the August date is speculation, not official so it could be pushed back. I thing you mentioned was the secondary viewing angle. When you move off center from a LCD, the picture tends to started washing out and is not as crisp and clear as in front of the display like a Plasma will be. Go to a store and witness this for yourself . Try to position yourself at the angle where the secondary seating will be. While not the best viewing environment, try to see these displays in person in the store and see what you like and don't like about them. The 2014 sets are just around the corner so things will probably change once the reviews start coming in.
Sony KDL-55W900A ($1,999)
Samsung UN60F8000 ($2,600)
Samsung UN65F8000 ($3,100)
Sony KDL-65W850A ($2,500)
Samsung PN60F8500 (Plasma) ($2,300)