All of my rides are alone, even my first tour, which was around the Big Island. Of course, once you get there, you aren't really alone, are you? There are so many others around, but you don't have to ride with them.
I think it was more along the lines of not seeing another cyclist for 14 miles that had me a little nervous. Kept checking my map to make sure I was definitely going the right way thinking I HAD to have made a wrong turn somewhere.