- Don't miss Les Baux. The village is touristy but the castle complex on top is fantastic and the views are to die for - you don't need to be a fan of scenery to appreciate them.
- Roman ruins of Glanum, walking distance from St-Remy
- Arles for more Roman ruins (but I think you've been already?)
- Day-trip to the Luberon for unmatched scenery and charming little villages full of vernacular architecture - what people build themselves, without an architect. See my fave, Oppede-le-Vieux (NOT to be confused with Oppede-les-Poulivets down the hill). Gordes and Roussillon are the most famous and thus the most touristed of the villages. I stayed in Joucas, positively tiny, all the charm, none of the tourists.
- For some really old architecture, visit the bories at Gordes - little buildings made with dry stone, no mortar, standing for 1000 years or more. There's a little village of them a couple km outside of town.
- Day-trip to Vaison-la-Romaine, Roman ruins, charming old town, massive market on Tuesdays.
- Don't miss the Sunday farmers-cum-antiques market at L'Isle-sur-la-Sorgue. Great for foodies. The roast chickens with potatoes and onions are to die for, taste even better than they smell. Bring your own utensils or do as I did, eat with your fingers and clean up afterwards. I imagine the paella is pretty great too, and they certainly serve up a single portion big enough for two.
- Pont du Gard, goes without saying.
- If you haven't already been, visit Aix-en-Provence, most charming of small cities. A great cafe city with a wonderful pedestrianized core. My favorite small city in the world.
- Aigues Mortes for a walled crusader town, standing since the 1100s. Also consider the nearby Camargue, around Stes-Maries-de-la-Mer, mostly for scenery and birds (especially flamingos), also white horses and black bulls. Caution: I spent three days in this area and did not have a decent meal, although the area is famous for sea salt and rice which is sold everywhere.
I have not been there in lavender season (yet) but understand that the area around Sault and the Abbaye de Senanque near Gordes are two places to find it in abundance.
Enjoy, it's a gorgeous area!