I use 3/16" line with an 8 foot length served at 10 psi. The Perlick faucet is 1.5' above the top of the keg.
I also have a section of 1/2" copper, of which 3" is in the cold fridge to conduct the heat away from the warmer tower temps. Helps reduce the temperature change and reduces foaming on first pour (great tip from someone here)
Primary #1: Border Crossing Vienna #2: 2H IPA III
Secondary #1: Berry Rhubarb Wine #2: Black Currant Wine #3:Cider
Kegged: Orange Pale Ale IV, Hidden Lake Nut Brown
Bottles: Spruced Winter Warmer, Surly Bender clone, Big 50 Barleywine, Framboise Lambic, Dark Belgian Strong, Kicked by a Moose Scotch Ale, Russian Imperial Stout, Sparkling Elderflower Wine, Barolo Wine, On Deck: Ice Shanty Bock