Provence (or Provence-Alpes-Cote d'Azur) is a massive region in the south of France, home to seemingly endless lavender fields and fresh sea air. There are a number of lovely towns to explore in the area, so definitely take your time on this stretch of the trip.
From Montpellier, head to Arles (just under an hour by car or train) — the town known for inspiring some of Van Gogh's greatest works — then wander through miles of lavender in Aix-en-Provence or the famous Senanque Abbey in Gordes (note: lavender season runs from late June through early August). Dive into the thick, turquoise waters of the Verdon Gorge, and finally, indulge in a seafood dinner and glass of Rosé at La Baie des Singes ("The Bay of Monkeys," a private beach and restaurant nestled in the Calanques of Marseille).
Oh, and save some room in your suitcase for the many lavender-scented souvenirs you're sure to find here.