there are lots of cast ons, (i know 30 or so)
some are stretchier than others.
i personally love a tubular cast on and 1 X 1 ribbing..
why not try the twisted german cast on? is a variation of long tail, its not too hard to learn, its much stretchier than standard long tail and it has good recovery (it doesn't stay stretched out looking)
here is a link
to one tutorial, if these directions don't work for you, google 'twisted german cast on" or "norwegian cast on" (another name for same cast on!) and find directions that work for you.