Hi prhymebeef,
I can only speak on behalf of prot pallies, but I'm sure Rigg will chime in later in this thread.
I talked a little bit about optimal single-target rotation in this thread:
http://www.bloodlegion.com/forums/viewtopic.php?f=27&t=15327.
I don't generally gear for threat stats at all. I actually try and minimize both hit and expertise as much as possible and haven't really had too many issues.
As for spec, my default single-target spec is the one I'm running at the moment except moving 1 point from Hallowed Ground and 1 point from Grand Crusader to max 2/2 out of Reckoning. My current spec is my Spine blood tanking spec, which is serviceable for single-target during farm so I don't really bother changing it from encounter to encounter.
Single-target glyph-wise is generally PRIME - SoT, ShoR, CS / MAJOR - Ascetic, Focused, LoH, but glyphs are generally one of those things that I change regularly multiple times during a raid instance depending on the encounter.
I hope that helps and thanks for dropping by!