Saint-Tropez was a very last minute add to our trip and it ended up being one of our favorite places. Because it was such a late add, we didn't have much time to think about or pre-plan our stay there which made for some fun surprises. I did get a few great recommendations from a lady I know in London who grew up on the French Riviera, but we otherwise explored on our own. The Port of Saint Tropez reminded me of Capri because of the abundance of high-end shopping and incredibly charming streets. It was beyond picturesque and full of color (pastel-colored shutters on every single building!) We shopped, had some delicious dinners, watched the sunset on the harbor, and walked the streets of this quaint little town.
I would recommend booking at room at Hotel Byblos, which is right in town. It was unfortunately sold out by the time we booked, but it's a darling spot in an ideal location. We stayed at Mas de Chastelas which we also really loved. It's incredibly peaceful, has a beautiful pool and excellent service.
When you're not shopping in town, you'll want to be at Plage de Pampelonne, Saint-Tropez's crown jewel of beaches, where you'll find bright blue waters and famous beach clubs. We went to Restaurant Tahiti Beach and Le Club 55 and I cannot recommend Le Club 55 enough. Live music, amazing service, charming blue and white décor, perfectly chilled bottles of rosé, fresh and delicious food... all on a vine covered patio overlooking the glistening blue water. Before and after your lunch, you can retreat to your reserved bed on the beach. With a restaurant, darling boutique and lounge chairs on the sand, it's a perfect spot to spend your entire day. (happy people watching!)