I'd recommend going for 24" in IPS or VA, so you don't get colour shifting.
I use three 24" BenQ 1080p VA panels. 27in will cost more, because you will probably want a higher resolution than 1080p for 27in monitors (my 4th monitor is a 1080p 27in and it's kinda grainy.. my 5th is a 50" 1080p TV and it's super grainy up close-ish). Three 24" is still huge and really breath taking too. Finding triple armed monitor stands that take anything larger than a 24" is tougher also, if you're into the stands. They're a little too rich for my blood, when I could spend that money on more keyboards.
Look for a display with thin square bezels, and then overlap them to halve the bezels!
I play sims too, DCS/FSX/Falcon 4.0/Rise of Flight/Assetto Corsa, a bunch of others. It's great for all types of games really, but playing sims with triple monitors and a TrackIR is really amazing.
Here's a couple of (old) pictures to give you an idea of what I have going on. Being pushed by two R9 290s, I can max/near max pretty much everything at 60FPS, some with AA, some without. My eventual goal if I get around to it would be two more monitors for a 5x1 portrait setup.. /drool.