Finally got myself a screen protector! I was waffling 'cause I hate the feel of most screen protectors, plus many get fingerprinty. Then I found out that they sell oleophobic tempered glass ones.
I ended up getting a Spigen glas nano one
http://www.spigen.com/nexus-5-screen-protector-glas-t-nano-slim.html, and it works like a charm; feels almost exactly like the original glass does. Relatively expensive @$35ca for one, but IMO, "protecting" your phone shouldn't mean degrading your touch experience with it. The only problem I've had is that the edge of the glass tends to build up a slight whitish edge where it traps a very small layer of lint all around the glass. Not a real problem for me, as I care more about the feel of the phone than the look of the (non-screen) portion of the face!