What CSS grid system fits the "ideal for small professional developers" tag, matching usefulness with friendly class tags and delivered with decent ready-to-go templates?
Hmm, I'm not sure that there is a "best" framework. I personally use the 960 grid framework (google it). It's simple, unobtrusive, and very practical and it's also easy to use.
I'm pretty sure Matt hit this on the head. There isn't a 'best'. It's what you prefer and what works for the situation. I personally use 960 myself. I've also found 1kb Grid System and YUI very nice and useful in their own ways.
Find one you feel comfortable with, learn it, and use it where you feel it helps you most.
I personally use BlueTrip as it combines a few of the different frameworks around. It allows me to tweak and choose what I need most for each project and get started with the CSS fairly quickly.
Just use GridFox, it's an add-on for Firefox. I don't use FX, but I do use this add-on for making everything align to a grid.