So many songs, so little time! Some of my all-time favorites have already been mentioned, including:
When we go Rolling Home
Rollin' Down to Old Maui
Time Has Made a Change
Pleasant & Delightful
Give Yourself to Love
Roll on the Day

A few that haven't yet:
Hard Times Come Again No More
The Rolling Hills of the Border
Music in my Mother's House
Song of the Soul ("And we will sing this song, why don't you sing along; and we can sing for a long, long time")
The Fox Hunt ("And a merry, merry, merry horn cries come, come away...)
Sorrow Away (?) (Am not sure if I have the right name for this one; searched the DT & didn't find it -- much to my surprise -- then Googled, also with no success...)
The first verse goes (I may have a word or two wrong):
    The time passes over so cheerful & gay
    Since we learned a new act to drive sorrow away
    Sorrow away (3x)
    Since we learned a new act to drive sorrow away

Perhaps that doesn't really count as a chorus song; since you don't sing the same thing every time but rather repeat the last line... but it's a fantastic song for harmony & singing together!

Cheers,

YY