I'm visiting a friend who recently moved for a few days in late March. What's something great for two friends to do that haven't seen each other in a year?
A carriage tour with Palmetto Carriage Company, a Culinary Tour with Charleston Culinary Tours (the Upper King one is better). I would eat at FIG - makes reservations, literally, one month in advance; and Poogan's Porch or Cru Cafe. Maybe Halls Chophouse. Stay in the historic district on the peninsula to be within walking distance to everything.
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Eat! Tour the historic houses. Spend the day at the beach. Visit the Aquarium. Great shopping. Wander through the streets South of Broad.