IMHO - for severely hit sites, starting over was the best advice. The ironic and painful thing is that my most severely nuked site just went up a PR point on the last update (useless info, I get it). That is probably because of my attempts to diversify links - but so far I've had no Google recovery on the big keywords.
But yeah, Google still sends me ranking for random pages I had never really messed with much before. But that site is still sitting at about 1/2 traffic of pre-penguin.
Diversifying almost everything and building replacement sites has been the strategy that is rebuilding my little corner of the web. I also went and woke up some stale sites I'd been using for feeders. Since they weren't really penalized, and had some age, they were pretty easy pretty up and spark again.
I have to agree with Ishmael, though Ishmael seldom agrees with me.
I wasted too much time crying over spilt milk and paying attention to the expert's recovery strategies.