Charleston’s downtown lodgings have three seasons: high season (March to May and September to November), mid-season (June to August), and low season (late November to February). Prices drop significantly during the short low season, except during holidays and special events like the Southeastern Wildlife Exposition each February. High season is summer at the island resorts; rates drop for weekly stays and during the off-season. Although prices have gone up at the B&Bs, don’t forget that a full breakfast for two is generally included, as well as an evening wine reception, which can take the place of happy hour and save on your bar bill. You should factor in, however, the cost of downtown parking; see if your hotel offers free parking. In the areas "over the bridges," parking is generally free. Depending on when you arrive, you can try to find on-street metered parking, as there is no charge after 6 pm and all day Sunday.
If you’re on a budget, consider lodgings outside the city limits, which tend to be less expensive. Also remember that longer stays sometimes translate into a better per-night price.