Setting headers for static content: Wordpress and W3 Total Cache

Setting headers for static content: Wordpress and W3 Total Cache

I'm looking for optimised settings for expire headers for my Wordpress
sites: I use Wordpress with W3 Total Cache plugin and Cloudfront CDN.
I set my headers for JS/CSS/media files to "cache with max-age and
validation ("max-age=EXPIRES_SECONDS, public, must-revalidate,
proxy-revalidate")" and 2 weeks (1209600 seconds).
Reason I set it to 2 weeks only (as opposed to 1 year by plugin's default)
I change my JS/CSS pretty often and I want to make sure user receives the
latest version.
Is this ok, or you find it counter productive (cache time too short - no
time to spread the cache world wide)?
Thanks, Betty