Basically, it comes down to what your eyes can handle with regard to clarity. The bigger the screen size the more area you are going to have to resize your gauges to your own liking. A 27" monitor is very close to real size when displaying the PFD and MFD on one monitor

Most users go with a dual monitor setup as most video cards have this option available now. This allows you to throw your gauges up on one monitor and have a full screen outside visual for another.

If the two monitor setup is not available to you, then I would go with at least a 24" widescreen display for a one monitor solution.

If you have a laptop, our software has network support so you can run the gauges on your laptop and user your primary PC to run P3D.

As far as brands go, we would look at Samsung or ASUS. Newegg.com has some good deals all the time on computer hardware.