Just an update for anyone who is curious. Spent Aug-Dec in Charleston, and I had a fantastic time. Chromekitty, Kman, et al. were right - for me, it was a very safe place to be, and I did a ton of walking alone. Pretty much everything south of Calhoun was safe - even the housing projects near Colonial Lake were fine - I frequently walked by there late at night. Someone I know was robbed near King St, but she was coming back late from a bar alone swinging a Gucci purse and tends to stroll slowly. Of course, I am male, 6'1", 200 lbs and fit, so use your best judgement.
There were police around the downtown area on bikes and in cars, but because people were always around, I never felt unsafe. I kept odd hours for work, and even driving @ 4AM there were people and visible police.
The rainy season wasn't a big deal (but then, there were no hurricanes in the area while I was there), but certain roads completely flood out while it rains (then clear out in an hour or so). The rain sometimes came in sheets, and the streets are not in the best shape, so walking was not fun. Sometimes when I had the time, I could wait 15 min or so and the rain would slow enough that I could walk home without too much trouble. Of course, in Aug-Sept it was so hot I showed up drenched even when it wasn't raining.
$1700/mo for a furnished apt. downtown was absolutely worth it. Although I paid less in Chicago to live across the street from Millennium Park, that one was unfurnished. In Charleston, I could walk to a ton of restaurants in the downtown area and if I got tired of those, the entrance to the bridge was just down E. Bay St. and I could be in Mt. Pleasant in 10 minutes. I could walk to the Farmer's Market in Marion Square, the shopping on King St, the tourist traps, work, and even became a member of the Aquarium.
Just north of the Market (and 1 block from where I was) is a 24-hr Harris Teeter supermarket which was perfect for picking up dinner on the way home. The library on Calhoun has a fantastic collection and there's a great bakery on E. Bay called Saffron. Fig is a pricy but excellent restaurant experience, AW Shucks was suprisingly good (I expected schlocky bad food - got the schlock, but my food was actually pretty good), Jestine's Kitchen was a guilty pleasure as was Yo Burrito, and TBonz and Molly Darcy's had pretty decent take out burgers. Big John's Tavern on E. Bay was OK in a pinch - and they are very friendly. Tsunami on E. Bay was not that great, Noisy Oyster was just OK, Taco Boy and Toast were sadly disappointing (after 3 tries), and stay away from the burrito places on King. There were lots of other good and bad restaurants, but those are the ones that come to mind and YMMV. E. Bay St traffic gets really heavy on Fri-Sat night if you're driving, so park farther away from the Market and walk if you can. Finding street parking is not fun, but can be done relatively quickly - just be mindful of the signs 'cuz they will ticket ya with a quickness.
If you get the chance, you have to go to an oyster roast while you're there (only during months with an "r" in the name). I'm not a seafood fan, but something about hot fresh local oysters worked out well.