A good rule of thumb when looking for a tv screen is to hold both arms out in front of you.. fist clenched and thumbs touching each other in a 16:9 format.
Now if you fists fit in the screen edge to edge from your sitting position ... that's a good size.
Try it... anything over that is over kil and you will find your eyes will get tired look for images on a wider screen.
 
In my setup... my monitors (eggs) are about 1.40 x 1.40 x 1.40.
ill post a picture tomorrow if you require...   but I need to clean  my desk!!!  :-)
 

Mesh
All is saw in the thread title was: advice on big-ass display
 
 
(I was going to suggest dieting......)

Due to some foot surgery I haven't been able to exercise for quite a while now...I've developed a big-gut display so your advice may still be good

garybrun
A good rule of thumb when looking for a tv screen is to hold both arms out in front of you.. fist clenched and thumbs touching each other in a 16:9 format.
Now if you fists fit in the screen edge to edge from your sitting position ... that's a good size.
Try it... anything over that is over kil and you will find your eyes will get tired look for images on a wider screen.
 
In my setup... my monitors (eggs) are about 1.40 x 1.40 x 1.40.
ill post a picture tomorrow if you require...   but I need to clean  my desk!!!  :-)
 

Your rule of thumb is confusing for me ...I'm probably missing something here but looking at this 25 " display I'm using I'd have to be more than 10 feet away to get my fists to fit in the screen edge to edge.
Like I say I'm probably misunderstanding but I hope a 40" display at 5.5 to 6 feet away is good?

lol...  Im talking large screens!  lol
The two display screens you are using as monitors fine...
But do what I said regarding the large screen... then its tthe correct distance away!

Consider another thing: videocard.
The larger the display, the larger resolution you will want to make the most of the real estate you get. I've been looking into 4k but not sure I want to spend that kind of money.

 
Some thoughts regarding 4K.
 
For my usage, especially Sonar (fixed size faders, etc), a 39" - 42" TV at 1080p is the most ideal. Due too poor eye vision, a 27" 1080 display would be my minimum. I do have a 21.5" Dell, but it's mainly use to place all the Windows icons or for a web browser with the zoom turns up.
 
Does anyone know of a formula to calculate how large a 4k screen might be, in order to retain the size of a 39" - 42" 1080 display ?

I know this is a huge necro-thread blast from the past, but I'm working on an article for my website about using a 42-inch 4K screen for DAW purposes, and ran across your question. 
 
The answer to your question is 82-inches; as calculated here:
http://isthisretina.com
 
I'll be posting other elements as I finish my implementation.

I have had two 32" and a 40", all HDTV's, and those worked really nice, but I ended up giving away one of the 32" displays.
 
I am still quite happy with the combo of a 32" and a 40" - I get lots of channel strips that are nicely readable when I put the console view on the 40", and I generally leave Track View on the 32".
 
Bob Bone
 

I have no where near the size you are talking about, but I am not looking to view it from any distance. My consideration was maximum screen real estate so I went for a 27 inch 2560x1440 rather than 2 24" screens. I prefer a single screen and the vertical resolution of 1440 is a big advance on 1080. 
 
This is setup great sitting at a normal distance from the screen. I certainly would not consider a resolution less than 2560x1440 unless you are working with multiple monitors.
 
The Sharp in the link is just 1920x1080 so you are not going to get a whole lot on the screen even though it is 48".

Glyn - which 2560x1440 screen are you using?