Hello! I'm glad to hear you're planning a trip to France. It's an absolutely magnificent country filled with diverse experiences.

Best Time to Visit:
The best time to visit France is during the Spring (April to June) or Fall (September to November) when there are fewer tourists, mild weather, and lower prices. Summers can get quite hot and crowded, especially in Paris and Marseille.

Route and Accessibility:
Flying into Paris Charles de Gaulle International Airport would be a preferable choice, as it offers extensive international connections. From Paris, you can use France's extensive train network to reach cities like Lyon, Marseille, and Toulouse. High-speed TGV trains connect these cities smoothly.

Accommodation and Booking:
Accommodation is plentiful in all these cities, with options ranging from luxury hotels to budget hostels. It's advisable to book your accommodations in advance, especially if you’re traveling during the peak tourist season. Online platforms like Booking.com, Airbnb, and the official websites of the hotels can be used for bookings.

Clothing and Essentials:
Pack light, breathable clothing for the summer, and warm layers for the cooler months. A good pair of walking shoes is essential as exploring these cities often involves a lot of walking. It's also advisable to pack a universal power adapter, as France uses Type E power sockets.

Health and Safety:
No specific vaccinations are required for travel in France beyond routine ones. You should have travel insurance covering health care. Major cities are generally safe, but be aware of pickpockets in popular tourist areas.

Local Etiquette and Respect:
French people appreciate politeness. A simple 'Bonjour' (hello) and 'Merci' (thank you) can go a long way. Tipping is not mandatory as service charges are included in the bill, but it's common to leave some small change. Respect local customs and dress modestly when visiting religious sites.