Watch the The I-vi-ii-V Progression online guitar lesson by Fareed Haque from Jazz Comping Survival Guide
How to play the I-vi-ii-V + 1 extension. Always try to keep a simple melody on top that 'leads' through the chord changes nicely. Experiment with holding different notes through the whole progression. Try holding the b3rd or the b5th or the 13th through the entire I-vi-ii-V progressions and see what you like.