I don't know what made me decide to try a double instead of a single crochet, but I have to say I am now smitten with this new look.  Plus they whip up much much quicker than the single crocheted coasters!

 

 

This just happened to be the color that I had on hand while babysitting,

 

but after I made a whole set (of 4), I switched out to another new color that I am starting to love and made another 4 piece set: