do not go 4k.. honestly 4K is nice but go ultra wide for a better game experience.. you will benefit far more from it!
example:
http://www.lg.com/us/ultrawide-monitors
It gives you an improved 3 screen setup feeling without bevels in between.
feel free to check the gamer(s) reviews of it.. and you will see what i mean.
Ofcourse you have to realise that 3 screens will end up being just as expensive as this monitor.. then again if you can affort an 980 that shouldn't be an issue either.
IF you want to go for a tripple screen setup go for an lower res ultrawide in the middle and 2 smaller side screens.
The 34 inch (its not very high just very wide) comes in 2 resoltutions:
2560x1080 Which is ideal for lower gfx cards or as setup in combo with 2 sidescreens.
OR
3440x1440 which is nearly 4k Resolution but in wide screen (better for game immersion!)
I own a 2560x1080 myself, and can positilvely say i enjoy it every day.. (I wont look back till a new rig + consumer Rift comes along).
The 34 inch does not look immense and doesn't disturb the living room.
PS. I do not own any stock in ultrawide technology ..

just personal experience .. if you want to enjoy the game most without going rift that is.