This year, I started off by using google maps as usual and here's a map showing all the places I'm staying.
Here are route plans for each day
You can plot routes on google maps, and it lets you adjust the route to avoid nasty roads etc., but once you've done that, I haven't found a way to export the customised route in a way that it reliably remembers your customisations, let alone be used when you're offline. So in previous years I've spent hours writing down a plan, based on having several browser windows open, and squinting at streetview to try and work out what signs say. This seems extra hard for RoI, where there appear to be hardly any road signs at all.
So this time, I have used Komoot to plan all the rides. It lets you enter start/end points and then adjust the route generated so you can make it go past nice places, and avoid nasty roads.
You can then download the route and have it give you turn-by-turn
navigation, even when you're offline, so I'm going to rely on doing that. I
did a quick test by plotting my normal route to work, and following its
directions, and it mostly got it right, so I'm not 100% certain but it'll be
an adventure.