I'm one to play favorites, but here are some honorables in no particular order, most not already mentioned:
"Watch your step."
"Be good to your families, come back and see our families here on the Feud!" (Louie's Feud closing)
"I'm JD Roth, hoping to make your house a Fun House."
"When you don't have time to think twice, Think Fast!"
"I challenge all of you out there to write, call, or e-mail to futility.com in the hope, infinitesimal as it may be, that on some planet, on some distant day, you might win Ben Stein's money (oney-oney-oney...)"
"The next time you're at a checkout counter and you hear the beep (beep beep), think of the fun you could have on Supermarket Sweep!"
"Tally ho!" (Gene used this often on MG)
And from an ep of Family Double Dare:
"This is your announcer Harvey reminding you to join us again next time on the only show on television rated PG...for pretty gross!"