Is a 27" so big that the spaces between pixels becomes annoying?

I haven't used one in depth, just looked at a 27" Asus 1080p in a store and thought it looked great.

Seem some folks recommend going to 1440p at 27" but that puts significantly more burden on your GPU.

http://www.tomshardware.com/reviews/crysis-3-performance-benchmark-gaming,3451-6.html
Based on this link and that the 770 at $400 is only moderately faster than the 680, you're not getting close to 60fps at 1080. And that card will be hard to squeeze into a $900 build unless you have a lot of components to reuse.

The move between 1080p and 1440p is a HUGE leap in clarity, and a $1-200 difference is not a big deal compared to the advantages you get for it. If you are really into gaming then you will be upgrading your GPU every 2-5 years, and your core system every 5-7 years, but your monitor can easily last 10+ years so it is well worth the money to get a monitor that you enjoy looking at, and may even be a bit beyond the rest of your system now because you are going to stare at that thing for a very long time.

If you are going to skimp on parts then get a more basic (but reliable) motherbaord, or a non-K CPU, or even value ram, because those things are easy and relatively cheap to replace down the road. It has been shown that it is much cheaper in the long run to get cheap $150-200 GPUs and trade up every year than to get a mid to high level card every 3-5 years (because you retain resale value better in 1 year time on a cheap card than in 3-5 year's time on a high end card).
But things like your monitor, keys, mice, power supply, and cables can last for many computer builds, and it is often much cheaper to get slightly more expensive high end parts that are going to last a while, than to go through several cheap ones every few years. As an example, my last monitor was a CRT monitor from the late '80s. I got it used from my dad's work, and it was a beautiful 21" CRT. I did not replace that thing until 5 years ago when I finally got my 28" flat panel monitor, but as much as I wanted a higher resolution and quality screen, the simple fact was that they cost $1500 at the time which was WAY out of my price range. But now you can find those 1440p monitors for $200 more than a 'standard' 1080p resolution monitor, which in the long game makes a whole lot of sense. What is really going to make you kick yourself is that ~1 year from now 4K monitors are going to be readily available, which is going to make the price of 1440p and large 1080p screens drop like a rock, so if nothing else I would highly suggest getting a cheap small screen in the mean time, or reuse an old screen for a little bit. Then, a few months after 4K takes hold and prices start doping then you can spend your money on a high quality monitor that will last you a good long time.

Like I said, the same goes for things like keybaords. On my first build I went through several sets of cheap keyboards in 2 years time. Then I bought a good quality Logitech set, and that lasted me 11 years, and would have lasted longer if my son had not pushed it off the desk onto the concrete floor. I am not saying that you need to buy something ridiculous. Just something a little above average.

For some items it pays to spend a little more, while for others it does not. Monitors are worth every penny you can throw at them.

Me and all my friends agree that for most things, a 24" 1080p monitor is big enough. They also agree that anything bigger needs to be a higher resolution.

I have 2 24" monitors about 2 feet away from me and they're ideal.

I have 2 monitors set up, both 27". I had every size of monitors from 15" to 27". I love 27". I have no issues with both of them. One is Dell S2740L- great monitor. Sharp with great details, no distortion or blur- the only issue is- it glass, reflects light and I can see myself in it. The other one is LG- works fine, not as great as Dell, but no reflection issues. No space between pixels.