Or... you could select a yarn weight [worsted/sports?] and the size of needles that would get you both the same gauge. Then each pick your favorite colors and... go to a knitting stitches book and pick out your favorite stitch: lacey? Cable? K/P ribbs?
Now knit a long panel, say 6' or more, using that new stitch. Make sure you have each panel the same length so you can and match and sew them up. Each panel can be a different stitch and a different color.
I did one like that for my mother and she has it out to this day!