Four instances that I know of, all involving "Pyramid"...
On the 20K, they used to offer $1,000 in bonus money for a perfect 21-point score in the front game. In late 1979 or early 1980, the 21-point bonus was changed to a TV set (which I doubt was worth $1,000).
On the syndie 25K in the '70s, they used to offer $2,100 in bonus money for a perfect 21-point score, but they didn't offer that for at least the final season (maybe earlier).
On the 1988 episodes of the 100K, the Mystery 7 trips were all pretty "local": Hawaii, Mexico, the Bahamas, Antigua, Jamaica, etc. Not that those are bad trips at all, mind you, but they used to give away trips to Fiji, Australia, London, Paris, Sweden, Switzerland, and other "far-away locations." Also, from February of 1987 on, I only saw them offer one car as a Mystery 7 prize.
On the 1991 100K, the first 14 weeks had the 7-11 for an $1,100 bonus on Mondays, Wednesdays, and Fridays. For the rest of the run, they had Gamble for a Grand, where you could win $1,000 if you got all 7 answers in 25 seconds. But if you decided not to shave 5 seconds off your clock or you didn't get 7 out of 7, you got nothing. So they made the bonus harder to get and offered less money if you did win it.
Brendan