The entire scene where they give the report. One of the great climaxes in film history.
The climax of the sequel also qualifies. "God Gave Rock and Roll To You", indeed.
Unfortunately, that version of the song (With Bill & Ted's guitar solos at the start)has never been commercially released, but Steve Vai's guitar solos & the KISS song have. Fans have managed to replicate the song as featured in the film with a little editing, and a little searching on the internet can bring up mp3s of the song with the solos at the start.
The time-travel causality battle between Bill and Ted and Chuck De Nomolos, too. Definitely shows that the boys are a pair of Genius Ditzes when it comes to time travel.
Bill charging the knight when he thinks he killed Ted.
Bill: YOU KILLED TED, YOU MEDIEVAL DICKWEEDS!
The historical figures running amok in the mall.
The scene with the future council. Words cannot describe.
Sadly, the version of Robbi Robb's "In Time" that plays in this scene (with the awesome, awesome lead guitar) is commercially unavailable. It is up on YouTube, however, and with a little finesse one can easily create an .mp3 file from it.
The band's unofficial mantra "Be Excellent To Each Other And Party On" also qualifies. No matter how ditzy the guys are, it's hard to deny that it's a most excellent philosophy to live by.
That music playing after Napoleon got kicked out of the bowling alley and walks proudly while putting his hat back on.
In a shooting script (and comic adaptation) for Bogus Journey, the boys had to confront their fears when the Evil Robot Usses make them manifest in the real world-Bill accepts a kiss from Granny Preston, Ted apologizes to Deacon and returns the Easter Basket, and both of them invite Colonel Oates in for snacks. They also fought their evil doubles hand-to-hand until the Good Robot Usses could get to them.