The biggest set I heard of lately was Jack Cooney and James Walden the first year at Louisville playing and ahead set of one pocket for $100,000. Cooney won that.
The most I've ever seen personally was in Atlanta with Cliff Joyner and Jack Cooney playing 'eight ahead' sets of one pocket, for $25,000 a set. Cooney won $75,000.
As for where all the action went, I've noticed over the years that it just comes and goes. When there's an environement where a lot of guys with some ready cash can gather together and gamble in various ways the action starts brewing. Before long road players and stakehorses show up, and as long as the big money continues to flow the action stays high and ready.