Four feet. Straight 5x for wets and scuds, but when I fish a dry fly I'll often use 8" each of 0x, 2x, and 4x, then 2' of 5x.
To the extent possible, I keep the line is out of the water so I don't think much tippet is needed.
My line itself is generally the length of the rod.
And as John has found out, it is amazing how many nearsighted, color blind, and dumb fish you find when you keep your line off the water.