Wiring Analysis Paralysis

Tangentially, think hard about how much wire you put in a given box.  Don't exceed the likely ability of the faceplate and jacks to actually FIT with the wiring behind it.  Says a guy with a few split (1 gang AC, 1 gang LV) boxes that have two RG6 and 3 CAT5E wires....  It's a bit tight getting things stuffed back into the box.  Especially if it's backed up to spray foamed insulation, leaving no wiggle room to push the cabling into the cavity...
Yup in the media room didn't do split boxes.  I did utilize split boxes for the on the wall LCD TV's in some of the rooms.  I did start with all Arlington boxes originally; well constructed.   Most difficult was doing the laundry room; but redid everything in there anyways (new floor, shelves, lighting).  Figured I might as well add the TV to the mix. 
I did add more electric and more in wall boxes in the family room sort of dividing up the boxes and using 6-8 keystone jack plates.  It was very tight.  IE: one keystone plate has some 8 catXX cables going to the patch panel.  I put speaker terminals on another one.  Also used tiny labels that I can't really see well unless I am right in front of the keystone jack.  For the in-house, satellite (did the two DTVs connectivity), cable and OTA TV stuff went to that thin RG-6 cable in the wall to the wall plate as it was more flexible and very thin.  I did not see any changes in reception.  It was a bit more expensive though.  I purchased short 1 foot cables; very thin stuff and aesthetically pleasing. (to me as I do not think the wife noticed or notices the cabling).   I did also do a whole thing related to the powered subwoofer that is more of a piece of furniture in the back of the room with its own LV / HV separate stuff.  You don't really notice the speaker; just hear it really.
Don't use a box for LV.  Use a ring.  Category cable (and HDMI) doesn't work well with a box.  Makes coax a lot easier, too.

To the OP - I mean wire a duplex outlet at normal outlet height, in the same stud bay.  Easy to come in a year later and extend line voltage to the drapery height, if needed.  I don't like blank plates; I try to avoid them when possible.
Neurorad said:
Don't use a box for LV.  Use a ring.  Category cable (and HDMI) doesn't work well with a box.  Makes coax a lot easier, too.
Yeah, those.  Not an actual double-gang box with the plastic insert in-between the halves.  Those would absolutely be the wrong thing for LV wiring.  I may, in one or two places, tack on one of those orange add-on clips to extend it to a triple gang size.  Or just whack another hole nearby.  
The short answer is, as I posted, be careful not to leave yourself without enough box to accommodate the wiring being pulled to it AND the connector schemes.
If you're doing spray foam, as a pro, I'd start looking at a 6" LV box like those that Arlington make....specifically designed for the bend radius and working.
I haven't read through all of this thread, but I just saw the Arlington box above. As part of my centralization of my AV equipment, I just changed some of the wiring behind me TV and used a similar Arlington box: