I use Warm and Natural batting in my placemats - it washes and wears great (and we have some messy eaters here, so they get washed regularly!) While you're making the placemats, it's easy to make trivets for hot pans while you're at it - just add a layer of a product called Insul-Bright (
http://www.warmcompany.com/ibpage.html) with the batting. I've been making coasters and trivets using the folded fabric strips for a long time, and layer my Insul-Bright to face the folded strips so I always know which side its on.