I currently have 2 23" monitors. I was thinking about getting a big 27" wide monitor to replace one of them. I don't think the two sizes will bother me, and I want more screen real estate for working in Sonar.
 
My question is, what resolution should I be looking at? I know my current monitors are 1920x1080. Is that fine with a bigger monitor? I don't like when everything is super small so I didn't want to go really high resolution, and I have the desk space for the bigger monitor.
 
Any thoughts?

Changing the monitor size without changing the resolution (same number of dots in a larger area) will make everything you see bigger, but it will not of itself give you any more "real estate" to display text or images. At the extreme you will just see the discrete dots (pixelation) that make up the image. If your screen will fit three images vertically above each other that are 640 pixels in height, at 1920 x 1080 on a small screen it will display exactly the same number of images on a big screen but the images will be physically larger and less distinct at the same viewing distance as they were on a small screen. If you want to fit more images on the screen, you will need a monitor that has more pixels or you will need to make the images smaller i. e. fewer pixels per image.

As slartabartfast mentioned. 1920 x 1080 will have the same real estate of any HD monitor regardless of the size.
 
My suggestion (if you have enough desk space) is to add a 39" - 42" Led TV to your setup (total of 3 monitors), skipping the 27" monitor. My 39" Samsung TV placed 3 to 4 feet away, looks great and not much pixelation that bothers. There is a setting in the Led TV that enables the input source to be set as PC. With my 39", Sonar views that can be zoomed in and out, the piano roll for example, can be zoomed smaller in a way you gain more real estate.
 
For now, getting more real estate is better by adding more monitor. There is a discussion somewhere that mentioned Sonar runs into display issue on 4K monitor.

Thanks for the input. So yea, no 4k, that seems like it would be a waste. And maybe to  getting a big LED TV instead of just a bigger monitor. I think I could potentially make it work... I think I sit too close though, it might kill me haha. But yea, I'll definitely keep in mind getting a higher res when I do look at monitors. I'm sure there's gonna be plenty of black friday deals. I don't know if I really want 3 monitors... Originally I was gonna do that but I think it would be a bit hard to organize with the way I work. I think I just want a big one and a normal one. I was thinking about turning one vertical too, because I like to be able to see a lot of tracks at once... but I guess at higher res, I'd already be able to see more tracks at once...
 
A lot to think about, but thanks for the input.