Another excellent resource: BRouter web client.

Also, if you like to explore, look at a map, pick out a few specific spots on a home to home loop, estimate general mileage and then take off, asking locals enroute how best to get from "here" to "there". It's a bit risky, and you have to know how to listen to advice (e.g. most people will be giving driving rather than cycling advice, which skews both time needed and suitability of roads), but it can be a lot of fun.