Here's the thing ... historical evidence is highly interpretive. This makes it very easy to interpret some fables, myths, legends, and even stories of fact to match almost anything ... if you try hard enough. While Sky made one good point, belief in religious myth does depend almost solely on faith, this does not give any interpretations of historical evidence any value, it also makes it impossible to show someone who lives by faith alone the truth in such matters.
The belief in Atlantas is FAR from universal ... and this "high tech" version is relatively new (Asimov and Lovecraft were the first to actually publish anything about this angle, though Lovecraft was much darker). To the people who originally created the myth (Greeks) advanced technology would have been steel-smithing ... as for intelligence, we have no way of knowing unless we actually find a place like the Atlantas legends mention. So that is all moot anyway and has little bearing on supporting another myth.
As for the "great floods", Ancient Egypt has a story of the Nile flooding, it didn't wipe out all life, however it did make the coastline of the Nile extremely fertile allowing them better resources along the river. Other than that they have no other flood stories. Oddly though even if they ALL did have such a story, and they even had fact to back those stories up, there is one huge flaw in using such stories to support this one myth. Time. None of the time lines come close matching up in synchronization to support them happening all at once. The Babylonians for instance are much older than all the others, and vanished long before the others did as well, they were the most advanced culture we know of in that era (they even put the Egyptians to shame in some areas) but they were far from enlightened in any way, also any tales about flood would have to be much older than other civilizations, thus outside of even their history and could in no way occur at the same time.
we'll see....someday, i have faith in science coming thru on one great flood, wiping out most of our civilization...they are closer than you seem to think....from what i've been reading.