No crank

I've recently been having problems when I go to start my car. Sometimes I need to turn the key 2 times just to get it to start to crank and other times if I drive for an hr or so on the freeway and shut it off the car won't crank at all if I try to turn it on a few minute later. I was thinking it might be the starter, but was wondering if there could be any other causes for this ?