I've knit with WOTA, Merino Style, Andean Silk, Andean Treasure, Suri Dream, Decadence, Shine and Twirl. The only one I wasn't
about was Twirl...just not as soft as I had hoped. But I bought it to knit little lambs, so no biggie. :D My favorite was Decadence...I
To get an idea of the gauge/how much yarn is required, look at the projects on their web site that are matched up with the yarns...also the newest catalog has a little chart by each pattern that hells you how many balls for what project...very handy. In general I've found their gauge/needle estimates pretty accurate, though th elast batch of Merino Style I got, there were some skeins that were much closer to worsted weight than DK, it seemed.
The color cards are great too...I have a KP gift certificate burning a hole in my pocket, and I'm definitely gonna pick up some more of those. Great for matching colors.
(And when you order, don't forget to go through a link here at KH, to help support the site! :D )