Ideal distance from TV to sitting/viewin position

Don't care about sound at this point.

Just for TV/Screen, what's the ideal distance to viewing positon for each size of 16:9 TVs

It depends on whether you are using it for normal TV viewing or you are trying to use it for Home theater.

(You state "Just for TV/Screen", which leads me to believe it will be used just for normal TV viewing, however, the sizes you state, leads me to believe it will be used for the a Home Theater setup.

If just for regular TV, I recommend a 3:1 ratio of viewing distance to screen size. (i.e. a 60 inch screen x 3 = 180 inches, or 15 feet, maximum.)

However, if you plan on using it for Home theater, I recommend a 2:1 ratio. (i.e. a 60 inch screen x 2 = 120 inches, or 10 feet, maximum.) Anything greater than a 2:1 ration will diminish the effect you are looking for. (Trust me on this. I have a 46" screen and I use the 3:1 ratio, and while nice for TV, it does not really give me the "Home Theater" effect I was hoping for. I really need a 70 inch TV, as I sit about 12 feet from the screen.)

My two cents worth anyway.
Here is a link for viewing distance calculator:
1.5 screen widths is a nice compromise between immersion and a soft image with high quality NTSC sources (DVD), and is a defacto average seating distance for home theater applications. This translates into the following viewing distances:

Diagonal -> seating distance
42" -> 55"
50" -> 66"
60" -> 79"
70" -> 92"

Relevant foot notes:

1. This is about 1% closer than you are to the screen in the last row of a THX movie theater meeting the 36 degree subtended field of vision recomendation. You need to think in terms of small movies screens not big TVs.

2. This is why one-piece consumer televisions are inappropriate for most home theater installations.


CLOser Still!!!

I am more sensitive to having to move my eyes and head to view the whole scene at one time. I tend to get a headache when I am too close. I have a 51" diagonal wide screen and sit about 12 feet away which seems all right now. But like I said, I am more esnsitive than most in this regard. My suggestion is to go to a tv store, sit at certain distances for a while, and see what works for you. good Luck
For TV, probably 3:1 screen widths (not diagonal measurement). So for a 65inch 65/1.15*3/12= 14 feet. You might be able to push that up to 4:1 for regular TV. For home theater, collapse that to 1.5-2.0 screen widths. 65/1.15*1.5/12= 7 feet. To sit farther away will pretty much require front projection. There are a lot of good digital projectors from $800-2000, check the AVS forums.
Well 12ft for a 92 diag. is just right for me. In about 1hr I'm thinking "I can see a little light between---can't we go bigger?" Some movies give me a headache----just never the screen size.
The distance that you sit from your TV depends more on the signal source rather than screen size. While viewing a regular TV signal, you should sit about ten feet in front of a 50 inch screen. However, with a high definition image, you could move up to a viewing distance of six feet or closer without ill effects. The picture is so detailed that it will seem like you are looking through a window instead of at a TV screen.