A couple of things to watch out for. One, the mapping sites are handy to plan out rides before you've done them. If you're not careful, it is possible to post a route, or pull up a route, that nobody has actually done, or maybe that no one would want to do. So it helps to have some alternate information on the route, either personal familiarity, or knowing somebody that's done it, or knowing it's a commonly used route, etc. Secondly, if riding in the summer, you need to have sources of water not too apart. If that's a semi-urban area, no problem, but if it's not, check and make sure where supply points are.