Definitely! Rennes, Saint-Malo, and Caen are wonderful cities in France each with its unique charm. Here are some travel tips for your trip:

Best Time to Visit:
The best time to visit these cities in France is during the late spring (April to June) and early fall (September and October). The weather is typically mild and there are fewer tourists.

Route and Accessibility:
You can easily access these cities by train from Paris. The train from Paris to Rennes takes about 2 hours, then it's about 50 minutes to Saint-Malo. From Saint-Malo, you can get to Caen in two hours by train. Consider getting a rail pass if you're planning to travel by train a lot.

Altitude and Acclimatization:
Being at sea level, you won't need to worry about altitude sickness in these cities.

Accommodation and Booking:
Booking accommodations in advance is advised, especially during peak tourist seasons. All cities offer a range of accommodations from luxury hotels to budget-friendly hostels.

Clothing and Essentials:
Dress in layers as the weather can fluctuate throughout the day. Don't forget to pack comfortable shoes for walking and exploring the cities. A raincoat or umbrella might also come in handy as there can be occasional showers.

Health and Safety:
Follow standard travel advice, like keeping an eye on your belongings at all times and avoiding deserted areas late at night.

Local Etiquette and Respect:
In France, it's common courtesy to greet people with "bonjour" (good day) in the morning or "bonsoir" (good evening) in the evening before starting a conversation. Remember to dress appropriately if you plan on visiting any churches or other religious sites.