For years the Sky Atlas 2000.0 has been the most popular atlas step up from a 6th magnitude atlas. The 8th magnitude limit is deep enough to enable users to find Neptune and the brighter asteroids. The large charts, while they can be a bit awkward to handle, are great to view, as they show wide swaths of sky.
The Second Edition brought some significant improvements: a useful step up to magnitude 8.5, galaxy shapes which show size and orientation, better representation of star magnitude, detailed charts of the Orion region and Virgo Galaxy Cluster. If you are debating between a used First Edition and a new Second Edition, get the Second; it's worth the extra money.
A few shortcomings remain. The charts are arranged in ascending order of right ascension. This presents problems with editions which are bound on the left side. When users reach the right edge of the chart, they have to stifle the instinct to continue right to the next page, force themselves to reverse direction, and turn--of all places--to the previous page instead. The same with the left edge. Charts should be ordered in descending RA like Uranometria or Millennium. Ordering by ascending RA is a pointless tradition.
Some of the versions are bound at the top, which solves the problem of the chart sequence--and makes the book less floppy to handle--but makes it harder to search for charts. Since the chart number is at the top right, the user cannot see what page they have their fingers on until the book is completely open.
The pages of the laminated versions are very sturdy for field use but hard to grasp and separate, especially when moist with dew. This and the previous problem could be solved by adding numbered, graspable tabs to the bottom of each chart.
A badly-needed improvement to the atlas came in a subsequent printing of the second edition: around the edges of each chart are noted the numbers of the charts which adjoin it. This greatly simplifies navigation through the atlas. It would be good to take this measure a step further and, on each chart, mark adjacent chart borders as well to save guesswork as to where each one ends and the next begins.
The many virtues of this atlas have been amply documented by other reviewers. The space I have spent on the shortcomings is simply an attempt to round out the picture. The many improvements already made to this work speak well of the publisher's commitment to an excellent atlas. The Sky 2000.0 is now only a couple steps short.
So which atlas to choose for your observations? I would completely ignore the 6th magnitude atlases on the market. For a beginning to intermediate observer, the magnitude 7.6 Pocket Sky Atlas is very well designed and affordable. For intermediate observing, the Sky Atlas 2000.0 is an excellent choice. For advanced observers who frequently go deep, I would suggest skipping the Sky Atlas and bringing both the Pocket and the Millennium along on outings.