I try and educate my clients on color management and challenges. This helps to set realistic expectations.
I work in RGB, because all of my clients will first view thier logos onscreen. They are pretty much deciding on their onscreen colors. Once settled on, I hand pick Pantone and CMYK values to best match the onscreen appearnce using reference books.
While in development, I am careful to avoid using colors that can not be reproduced in CMYK. Since CMYK colors onscreen are actually represented in RGB and rarely accurately represent the printed results of those values I don't present my work in CMYK.
I've sucked it up and bought several different Pantone books. They've proven invaluable and a worthwhile investment! My favorites are the Bridge set (coated and uncoated) .... they show Pantone swatches next to CMYK (values given) and suggest RGB values for onscreen purposes. I bought my set for $125, I think.
http://www.pantone.c...px?pid=286&ca=1 I used to manually compare process chips to pantone spots. Still do sometimes. It was tedious, but effective. My process chip books are cumbersome, but they can come in handy if clients want to keep a chip for reference.
I always compare matte and coated versions of a color. There are times when a different color assignment for each is advised.