The major decisions include where (distance, how many days), when (season), and how (transportation to the starting point and from the ending point, or a round trip; organized or self-support tour; lodging and meal options, etc.). For self-supported. The biggest task is to decide on the routes. You may select routes designed by professional organizations (e.g., ACA), public routes designed by other riders (available from apps such as RidewithGPS, Strava, Komoot). If none of them fits your plan, design yourself. The common tools for route planning are:
Google map: It has information of local bike paths and tries to use them. It is getting better recently perhaps with the help from AI. It marks with green separated bike trails and bike lanes on roads. It shows very climbing profiles along the routes and warns steep climbs. It does not have information on the road surface conditions (paved vs unpaved). You can get on an unrideable rough dirt road without knowing until you see it.
RidewithGPS: This is the most popular one for cyclists. It is designed for cycling and has much more functions than Google map (e.g., known unpaved road or trails are marked). It synthesizes information from routes submitted by users and detailed local road/trail systems. It provides detailed terrain (climbing) information. It is not easy to use for starters. But once you know how, it is very powerful.
Strava: This is another popular app for cyclists who like social media. I don’t use it.
Komoot: More popular in Europe than elsewhere. I only used it when I rode in Europe.
Both Google map and RidewithGPS provide turn by turn information (cue sheets) and navigation functions. Navigations drain batteries. When GPS is on, you can simply watch your current location on their maps without their navigation on and still know where to turn. This would use much less battery power than navigation. Both apps share a same problem: Updating information. They can send you to private properties that owners refuse to let you through. Road and bridge closures are often not included in their routes. Besides, they try everything to get you off main roads and streets even if they have wide shoulders to ride on, at the price of big detours, steep climbing, and poor road conditions.
When you have a choice, designated bike trails are almost always the best. Exceptions are some gravel trails that have very rough or loose surfaces that require fat tires (> 50 mm), which most long-distance bikes are not equipped with. A big advantage to ride on rail trail is that railroad grades are usually less than 3%. Trades off between major and minor (local) roads are: Major roads can have busy traffic which should be avoided if they don’t have bike lanes or wide shoulders for bikes. They usually do not have greater than 7% climbing, at least in the US. Local roads may go up and down more. They may not have shoulders.
Other important factors that can and should be included to your planned route information: places to get water and food, alternative locations to spend the night if you can’t reach your destination of the day, the nearest bike shops and healthcare facilities. These can be tricky in remote areas.
Chidong Zhang's WA2MA Bike Trip 