Franz Xavier Witt wrote quite a lovely choral Offertory for this Sunday (Lent II, as well as OT XXIX). It's mostly SATB until the last tiny section where it splits to SATTB, though you could probably engineer it to not split if you only have 4 voices.

It is available on CPDL: http://www1.cpdl.org/wiki/images/sheet/witt-med.pdf

I think most choirs could have a lot of fun learning this piece. It is quite simple and easy. Maybe consider bookmarking it for next year.