Hello! It's great to hear that you are planning a trip to Rennes, Saint-Malo, and Caen. These are all beautiful locations in France.

Best Time to Visit:
These French cities are enjoyable to visit year-round, but the ideal time to visit is from late spring (May) through early fall (September) when the weather is pleasant and outdoor activities are possible. July and August may have larger crowd due to summer vacations, so plan accordingly.

Route and Accessibility:
You can reach Rennes easily via flights from major cities. For internal travel, France has excellent public transportation. From Rennes, it is a short train journey to Saint-Malo and then you can visit Caen using the train or bus services.

Accommodation and Booking:
All three cities have a variety of lodging options ranging from luxury hotels to budget accommodations and B&Bs. Booking can be done online using various hotel booking websites. Early booking is recommended, especially during peak tourist season.

Clothing and Essentials:
Pack comfortable clothing according to the season of visit. Summer means light clothing while autumn requires sweaters and light jackets. Winters demand warm clothes. Do not forget to pack your sunglasses, sunscreen, a good pair of walking shoes and a rain jacket because weather can sometimes be unpredictable.

Health and Safety:
France is generally a safe country but like any other tourist places, be cautious of your belongings. Travel insurance is recommended. Also, keep emergency numbers handy.

Local Etiquette and Respect:
French people appreciate politeness so it's good to know basic etiquette like greeting shopkeepers and saying 'please', 'thank you' and 'excuse me' in French. Avoid loud conversations in public places. Respect historic and heritage sites.