We also went the super casual route for or save the dates. We actually did email save the dates using paperlesspost.com
It was a really fun and inexpensive option for our save the dates.
We chose this route because of the cost savings but also because with a destination wedding there is so much information that you want to provide to your guests, that we decided that an electronic message in where the guests can click on a link was just perfect!
We printed just a few on postcard paper and sent those to the older generations in our fam, but other than that, everyone got the paperless post cards and loves them!