I do respect your view point, certainly it is the natural instinct to survive no matter what. However, as you've noted, there are many complications. The only real option at present is inhabiting the moon, mars or perhaps a moon on another planet in our solar system which would pose many of the same threats as we have on earth (the only real reason for doing such a thing is if we have completely destroyed the earth beyond repair; and yet preparing one of these planets for this purpose would surely take hundreds of years).
Now, without relying on wormhole theories etc, I'll present the idea of building a vessel that could travel to a planet outside of our solar system; a journey lasting thousands of years if we're lucky. (Maybe there is a better plan of action, please tell me if you can think of one.)
Assume: we have found the perfect solar system with the perfect planet (almost identical to ours but untainted by intelligent beings) to aim towards; we have calculated the path with an astounding amount of precision (now I don't doubt this, but then there are things to consider like dark matter); we have cryogenic freezing nailed (if it's possible); we have a vessel that can self repair and with almost autonomous intelligence, as you've said; we have chosen the 1000 best people on the planet to insure a good diversity and quick expansion (never mind a government who will think in this way and be ruthless about selection, even towards themselves). There are probably many other things I've missed, but I think this is paints a fairly stretched picture as it is.
Is it not just pure fantasy? Perhaps we should readdress this in a thousand years, then I might have to eat my words (certainly the sign of still being alive would point to this!). At the moment however, I'd rather hold on to the hope of a 2012 transcendent being theory.