Of the many interesting concepts to come out of medieval France, musique mesurée stands out to me as both a simple and stimulating approach to vocal composition.
In brief, the longer syllables are assigned a long note value while short syllables are given out in short note values.
Today, compose a piece for mixed choir. Beforehand, come up with your rhythmic assignments. For instance, you might decide long syllables will be expressed with half notes and short syllables with quarter notes. You may be as simple or complex as you feel. (You might even extend this concept by assigning motives rather than single note values to each syllable type.). Values may be subdivided or truncated by rests.