If you're not experiencing much issues with the games you suggested then you're not necessarily in need of an upgrade.
As far as up and coming components, Intel has their Haswell 4th generation processors coming out sometime this year, however I think they're only directed towards mobile devices such as laptops & tablets.
The 6770 is probably a little weak, my 5770 is still holding true for D3 & WoW but I'd like to get my hands on something more powerful. I think your processor is what's currently bottlenecking your build imo.
If you are going to upgrade you're looking in the right place @ Intels i5's, the 3570k is highly recommended and preferred for most builds. 660 ti is also a good choice if Crysis 2 / D3 / GW2 are the only games you're playing, could even get a better card for better longevity.
What's your budget for a new build monitor included assuming you have the means to do a full system upgrade?
Screen size has nothing to do w/ graphical performance only the resolution and refresh rate.
I would wait to be honest and see what Intel is coming out with this year before I get a new CPU if your doing decent in games atm. Also new GPU's are going to be coming out and prices are going down on the current gen every month it seems esp on the red team.
What I meant by the screen size is that I'm happy with 1280*720 on 19.5". I do however want a bigger monitor and that resolution will need to be upped on a 21.5" screen. Not sure how much that will effect performance.