Marseille is beautiful. The Calanques are a must-see by boat, as are the Chateau d'If and the island of Frioul. The city itself is also very nice, it is fun to just wander around and explore different neighborhoods beyond the Vieux Port and the Notre Dame. Great food and nice people.
Marseille and Cassis are amazing and the Calanques just stunning! We loved visiting the caves and jumping off the cliffs. In Marseille, we highly recommend taking the fun little train tour - a highlight of our day trip! Cassis is quiter but the ideal place to spend a week soaking up the gorgeous weather.
Marseille is perfect for a long weekend in the Calanques or to spend a week and go a bit further to Porquerolles. The Vieux Port, in the heart of Marseille is an excellent base, with all that you need for vittalling the boat and very convenient in terms of transport infrastructure. In high season it is important to book any marinas in advance (e.g. for Cassis need to call at 6am the same day to try to get a place). Keep an eye on the weather, as a strong Mistral might be a big constraint to your options.
We where visiting Les Iles by boat and it was a very nice trip!
Our skipper Emmanuel drove with us around the whole island.
We could cliffdiving and snorkeling there and hat a great sight!
Even though there where many boats around because of the nice wheater, we could find nice and even lonley spots.