Flying into Marseille then traveling onto Avignon to catch a river cruise. Recommendations for best transportation, please.
Train. There is local service from Marseille Provence airport to the centre-ville station in Avignon. Or take the railroad's shuttle bus to Aix-en-Provence TGV station and a high-speed train to the Avignon TGV station on the city's outskirts (there is a short shuttle train to the centre-ville station.)
http://www.marseille-airport.com/access-car-parks/access/by-train-or-by-bus