I've lived in the Charleston area my entire life. Here's my take:
Charleston is a major seaport city (4th or 5th largest in the US). Despite this, the entire Charleston area has ~500,00 population. So, it's certainly not Miami, or San Fran. From my prospective, this is a very good thing. The harbor itself is a natural deep water port created by the meeting point of three major rivers, east to west: The Wando, the Cooper River (properly pronounced Cuppa Rev'u) and the Ashley.
First: No-one boats during the week...this afternoon on a beautiful 84 degree Thursday in September, I ran my boat 17 miles through the harbor and up the mighty Wando River. I passed no more than 6 pleasure boats & 1 ship who were also under way.
Charleston Harbor is similar in size to San Deigo, so there is plenty of water for cruising.
Note: from the harbor looking back at the skyline at sunset behind the city, you won't see looming sky-scrapers typical of most large coastal cities. You will notice many smaller, more hodge-podge height building tops... you will also notice the dramatic points of numerous tall spires from the myriad of church steeples on the penninsula. Hence the name, the 'Holy City'. They have written books about it...
Oh yea, speaking of tall, connecting Mt. Pleasant to the city of Charleston is the brand-spanking new Ravenel Bridge that has re-defined the city's skyline. It's officially the longest cable-spanned bridge in the USA. It's towers can easily be seen from 10-miles offshore in broad daylight. At night-time, some folks say that it's breathtaking. It is also known affectionally known as the 'Cuz-way'...don't ask.
Charleston is a very historically significant city and it practically revels in it's role in US maritime history (Fort Sumter, the "Bat-tree",aka the Battery, Blackbeards seige, the Confederate submarine Hunley, USS Yorktown, etc). Hence at the very least, there is no shortage of trinkets for sale.
The Harbor entrance is jettyed and very well marked, permitting safe entry/exits year round, regardless of weather. Night-time operation is very popular as a result, just be mindful of the ships and their right-of-way.
The City Marina's new Mega-dock is probably the best place to tie-off to once you arrive. It's situated right where the Ashley River and the ICW meet to form the western part of the harbor and adjacent to the SE Regional office of the US Coast Guard. As such, it's a very safe place to berth. You have arrived and a walk, bike or a cab will get you downtown within minutes. There are 4 other major marina's surrounding the harbor, and 5 additional marinas within an hour's cruising range.
There is only one federally recognized anchorage in the area, so we have the rag-baggers pretty-much contained (until a late afternoon rum-wafted breeze blows, then all bets are off). Shem Creek, east of the Cuppa (Cooper), sports the largest collection of dockside dining...7 different dockable locally-owned restaurants. Remarkably enough...no HOOTERS! Lot's of commercial fishing boat docks lined up there as well...very photogenic area.
Officially, they call our weather "sub-tropical". At one time, I thought I knew what that meant...

I would say it's pretty much boat-able weather 9- months out of the year. My hard-core fishing buddies say all 12. There are 3 certifiable yacht clubs, dozens of regatta's and fishing tournaments, both inshore & offshore. Many folks (me included) cruise up or down the waterway (ICW), dropping anchor in the sheltered waters behind the many small coastal inlets between the barrier islands just north and south of Charleston.
I could go on about the city's Southern charm, 'Gone with the Wind', the Gardens, the Inns, restaurants, golf, etc., but I've probably said too much already. Suffice it to say that Charleston is a very cruisable location, as long as you don't have ADHD.
On second thought, I think you should check out Myrtle Beach or Jacksonville.
