I can't handle it on "best for retina". I've been used to at least 1600x1200 since the late 1980s and 2560 across for the last few years on desktops.
For me the highest "standard" resolution (1920x1200) is usable for most purposes, occasionally switching to 2880x1800 for heavy use, photo editing, lots of windows. Although "best for retina" is very pretty, there's too little real estate to do anything useful.
I thought I would be using mostly 1680x1050 by I find myself using mostly 1920x1200 most of the time. I find it very readable, I love the additional screen real estate and it just seems natural (nothing looks too small or sized incorrectly). This reason alone sets the rMBP above the cMBP for me.