I normally ride by my own. Mainly because I don't cycle because of the sports aspect only. I want to see new surroundings and will also stop frequently to take pictures or just enjoy the scenery. I average around 10-12 mph. Too slow for any group ride. I use a combination of Google maps, Google satellite view, Google street view and the Garmin app to plan my routes. I try to stay on trails wherever possible and try to avoid roads with a speed limit of more than 30mph.
Google maps is outdated in regards to trails in our area. Therefore I quite often use the satellite view to check for new trails or trail expansions or new roads. Satellite view is also great to check for other obstacles such as fences, creeks, grassy areas you may be able to cross. Yes on some of my routes there may be sections where I have to push my bike or lift it over obstacles. Satellite view is also good for rides across parking lots or through back alleys to avoid streets with traffic. All these "special" sections you cannot really plan with routing tools. I then right it down on paper.
As for riding on streets I use Street view to check how the roads look like. Are there shoulders or bike lanes? Are there wide side walks? Are there traffic lights and do they have crosswalk signals?
Out of all these tools I build my routes. And once I have ridden it I save it as a new course in the Garmin app.