Recently a Textkit study group has formed to read the Discourses of Epictetus. Naturally I slurped up the text into Scholiastae, and one scholiastic activity I've been involved in is creating a list of the most common Stoic terms and idioms used in Epictetus. A few weeks ago, in the course of my hunting down references, I discovered that Keith Seddon (“The Stoic who Never Sleeps”) in 2005 came out with a translation of Epictetus' Enchiridion. In addition to the Enchiridion, however, the book contains a translation of the Tablet of Cebes — a work I had never heard of until that point.
It turns out the Tablet was once frequently paired with the Enchiridion, with Theophrastus' Characters often rounding out the collection. The Tablet is a brief, 1st century dialog introducing Plato's puzzling doctrine of pre-existence, and the value of philosophy in general (it is invariably compared to Pilgrim's Progress in English references).
It is astonishing to me that the Tablet has no showing in any of the many introductory and intermediate Greek textbooks I have seen in my life. The work, along with its usual company, was once quite popular, both in Greek and in translation — into Latin, of course, but also into European vernaculars and even Arabic. It seems well suited to beginners in Greek. The language is not too trickified; it is short and could be read entirely in even a quarter-system school schedule; it introduces philosophy, a subject which doubtless draws more people to Greek in the first place than does Xenophon; one can even bring in discussion about Hellenistic and Imperial intellectual trends — how many philosophical dialogs start with ekphrasis?
The Wondrous Textual Powers of the Internet give us several reading options.
Drosihn's 1871 Teubner seems to still be the standard critical edition, but I'll gladly hear correction about that. It is available on Google Books, a copy of which is also at Archive.org.
C.S. Jerram of Oxford has a 1878 school-boy edition with extensive notes, including many useful to those with wobbly Greek. Again available via Google Books, with a copy of the Google scan at Archive.org.
Richard Parsons brought some Yankee ingenuity (well, Ohio Wesleyan ingenuity) to Cebes, producing a 1897 edition with less copious notes. It does, however, have a brief vocabulary at the end, which makes his book prime bus-to-work reading material. There are several indifferently produced off-prints on the market now, but if you don't love your printer too much, there are again both Google Books and independent Archive.org editions.
There is a 1997 Bryn Mawr Greek commentary by T.M. Banchich, about which I can find little information.
A project at the Université catholique de Louvain has text versions (in Greek and French). I am as yet uncertain, given the editorial markings, of the provenance of their text. And I do wish they had a clear statement of copyright for this very tasty pot pourri.
Finally, Archive.org houses a rather florid 1910 English translation — to say nothing of the typesetting — The Greek Pilgrim's progress; generally known as The picture.