I use a modified version (rotated 90) of the plans at BeeSource.click image for larger view
I also like the ability to close them off with the slide in tray. I know a lot of folks successfully use SBB year round, even in the North, but I do believe closing it off makes it easier for the bees to keep the brood warm in the early spring. The tray also makes monitoring mite drop real easy.
I also tried one hive with no bottom board last year, and was very happy with it. Obviously only one hive is not very scientific, but it was an interesting and educating experience.