I prefer dishcloths that are about 6" or 7" squares. Larger or smaller pieces are still useful for other things. What pattern are you using for your place mats? I was playing with blanket rib stitch yesterday (yeah, making a dishcloth) and think it would make a nice place mat.
Cheating is an option. . . . Cheaters never win and winners never cheat, but smart knitters who want to retain an iota of sanity do, cheerfully. ~~Kory Stamper