12th fret angled 45 degrees toward the soundhole seems to be a good place to start for most people. If you wanna do stereo, or two tracks panned, you can put one at the 12th, and the other one around the bridge to get a fuller sound.
As far as distance from the guitar, I like 12-24" for most guitars and most rooms. 18+" is best for me.
Play with mic placement, and I'll bet you can get something you really like. Check out SDCs like Oktava MK012, MXL603, Rode NT5, a bunch of others that others will chime in one. Most people really like SDCs for Acoustics.