One can find air times for The Tonight Show by opening a TV Guide and looking either under a talk show category for the show to see what channel it is on or just by looking at NBC air times and finding the time the show airs.
Buddy Rich appeared on The Tonight Show 43 times.
David Steinberg
Laura Bush appeared eight times on The Tonight Show, once with Jimmy Fallon and the rest with Jay Leno.
Bob Newhart
yes
Bob Newhart
The Tonight Show has aired 11,461 times as of this writing. It first aired in 1954 and is the longest-running talk show in history. Its hosts have been Steve Allen, Jack Paar, Johnny Carson, Jay Leno and, most recently, Jimmy Fallon.
Yes, he appeared on The Tonight Show starring Johnny Carson four times but all his guest spots were prior to his presidency.
I can find three appearances.
The Tonight Show was created on 1954-09-27.
Terry Bradshaw has been on the Tonight Show with Jay Leno 49 times as of June 14 th 2012
Bob Hope holds the record for the most appearances on The Tonight Show, with over 100 appearances. Hope was a beloved comedian known for his quick wit and charm, making him a favorite guest on the show.