Should I go to St. Tropez? And has anyone gone to Sainte Agnes?

St. Tropez is by the beach and it is a very picturesque village. Sainte Agnes is up in the mountains. It has its own charm but for me , I like being near a seaside village.

I haven't been to St-Tropez and cannot comment on its charms, but it might be helpful to know that it doesn't have a train station. If you take a boat over there, you'll need to either return by boat or take a bus to St. Raphael and pick up a train to Nice there. This will make for a fairly time-consuming trip.

I also haven't been to Cannes, but I have been to Antibes and liked it very much.

St Tropez has a central village area and port that has charm and yacht-spotting possibilities, and there are high end luxe opportunities (or at least pricey) all around (some a bit more tucked away in the hills). Summer is the crowded season; I've only been in the shoulder season. There are indeed ferries/tours that leave Cannes and Nice. Note that the famous Pampelonne Beach is 3+ mi away from the central port area, in Ramatuelle (there is a bus or obviously, taxis). There are a number of short boat cruises and excursions (like from Cannes to St Honorat) if you want to admire the coast and water instead.

St-Tropez is small and picturesque in a post-card fashion. Even though it is not an island, most take a shuttle boat from the coast so it feels a little isolated. Lunch, an hour lusting after the rich folks' yachts, and no thought of the beach (French tourist beaches are too over-organized to promote a calm mood) so a half-day was sufficient.

We once rented a cottage in St. Agnes (ahn-yez) and enjoyed the experience. The views are quite special there, both looking down towards Menton, plus within the valley that envelops St. Agnes itself. There is another, twin village across that valley which serves as a good hike destination. The GR51 hiking route is one of several in the area. In St. Agnes, there are also the well-preserved remains of the Maginot line military fort from the period between the two world wars. The St. Yves restaurant is our kinda' place, a laid-back family place wizout pretense (VG fish dishes and also 'sanglier' 'wild boar; open for breakfast). One of the other, more chi chi eateries with a panoramic view, tolerated cigar-smoking tourists. That attitude disappointed us. The village has a tiny church square plus a peaceful cemetery lane. One panorama there is the Col St. Sebastien.
The cliffside town, Saorges, is further up the valley and would make for a great stay as well. Bon chance.
I am done. The end.

Thank you so much for the replies. Very helpful.