The number 1 issue for me is to be consistent in the TR; if there are already 66, I use 66. Changing between 66 and 110 is a pain. It is annoying to punch down and a bigger pain to troubleshoot.
In a greenfield site, I really like the Systimax Visipatch system. It is basically a 110 system on steriods. It uses 110 C4/C5 clips to terminate the wire, but the mounting bracket is different. Voice circuits are built with cross connect wire, like usual, so you have full flexiblity to use the pairs anyway you need. Data connections are made with special patchcords that have 110 clip on one end and an RJ-45 plug on the other. The 110 clip has a 180 deg fold, so you end up with a nice neat panel. The clip also has a label space on the end! Patch panels take up way too much space and are twice the cost of Visipatch. I also think Visipatch easier and faster to install.
For the PBX rooms, I've been playing with Krone and Systimax's Z-IDC system. Both use a special test plug which allows you to open the circuit and test in either direction *without* touching cross-connect. I like the system but they are a bit pricey. I like them on the switch port side but they are a bit overkill (and pricey!) on the cable side. Given my stated aversion to mixing termination methods within a TR, I've not wholly convinced they are the way to go.