Let's not forget:

Every Picture Tells a Story
Blue Eyes Crying in the Rain
Mainstreet (Bob Seger)
And any number of Bob Dylan tunes.

There's a lot of great songs out there without a chorus, but I think the general public really likes that chorus they can sing along with--as Jean mentioned.

In my neck of the woods, the most popular bands are those that play a combination of new country and classic rock. It seems like these bands pack the dance floors often because people know the words to the songs they're playing. Two of the most popular bands in these parts have "Mony Mony" and "Old Time Rock 'n' Roll" as staples in their set lists--and when they play 'em, the folks hit that dance floor (drives me crazy, BTW) By the same token, I've seen bands clear dance floors because they play an original tune or one that's obscure. I know that's weird--I always thought you danced to the beat of a song--but in these parts, folks dance to the familiar words. Then again, I don't live in an area noted for its open-mindedness and progressive thinking LOL.

The most unfortunate thing is that bands playing original music often play to empty rooms. I live in a very rural area, so maybe that's why. People here like the familiar and shun just about any form of change. Sad, but true.

Eric