There are way too many great restaurants in Charleston, and it's hard to strike out. Below are are a few places to have drinks before or after dinner ( no 21 year old hipsters drinking PBR here). There are also bike taxis everywhere, so the two (three) of you can get anywhere in minutes. Most of these are on Upper King street away from the tourist-centric area.
DRINKS / COCKTAILS *there's downtown, and a few out on Sullivan's Island, Shem Creek, and Folly Beach for a more chilled out atmosphere
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The Rooftop at Vendue (overlooks downtown- if weather is nice, it's awesome)
http://thevendue.com/restaurants/the-rooftop/
Proof- on upper King Street, directly across from Hall's Chop House. Excellent gin joint, great bar.
http://www.charlestonproof.com/
Prohibition on Upper King Street- live music (swing) most every night; best Irish whiskey selection in SC.
http://prohibitioncharleston.com/
The Cocktail Club (Above the Macintosh)- upscale, but great drinks/people watching
https://www.thecocktailclubcharleston.com/
Dunleavy's Pub out on Sullivan's Island-- awesome local bar that has a great beer selection, and a fun place to catch a game. There are a string of restaurants right next door that are great places to grab lunch and hang out as well.
https://dunleavysonsullivans.com/
Tavern and Table: this is in Mt. Pleasant across the bridge from downtown (10 min) and is on Shem Creek. Hang out, drink beers, and watch the shrimp boats come and go. Dolphins routinely (and I mean routinely) swim by.
https://www.tavernandtable.com/
St. James Gate Irish Pub on Folly Beach (hey, I live here...) Another great place to drink beers and catch bowl games or NFL. Right downtown on Center street on Folly Beach; everything is walking distance and there are lots of other restaurants around. About a three minute walk to the actual beach from this bar.
https://stjamesgatefollybeach.com/
RESTAURANTS
Hall's Chop House- best steak house in town.
http://hallschophouse.com/
Hank's Seafood - top three seafood, and top five restaurants in town.
http://hanksseafoodrestaurant.com/
Husk-- authentic Charleston food; all locally grown/caught.
http://www.huskrestaurant.com/
Xiao Bao Biscuit-- Vietnamese food and it's awesome. Very chill atmosphere and good beer and drink selection
https://www.xiaobaobiscuit.com/
FIG (Food Is Good) local restaurant that is out of this world good.
https://eatatfig.com/
ATTRACTIONS
Patriots Point Naval MuseumHome of the WWII aircraft carrier USS Yorktown, Destroyer USS Laffey, and a Vietnam era Naval Support Base
https://www.patriotspoint.org/
Bulldog Tours-- everything from food / ghost / history tours. May not be the best thing with a three year old in tow, but up to you. They are the best in town hands down.
https://www.bulldogtours.com/
The Old Exchange and Provost Dungeon: this is right downtown Charleston at the head of Broad Street. Check out where George Washington addressed the city in 1790, see where Blackbeard the pirate was held in the dungeon, and where the Declaration of Independence made a stop.
http://www.oldexchange.org/
Boone Hall Plantation in Mt. Pleasant (again about 15 min from downtown) this is where scenes from Gone With The Wind were filmed; it's an iconic Southern plantation home, to include several original slave quarters on the property. Ryan Reynolds and Blake Lively got married here, but later felt regret because, well, you know...history actually occurred.
https://www.boonehallplantation.com/
Fort Sumter Tours: You can take a 20 minute harbor cruise out to Fort Sumter and tour the old fort. This is a really cool thing to do, and they give you one hour on the ground before the boat departs. Great view of the surrounding area as well.
https://fortsumtertours.com/
Lots of recommendations, and I'm happy to take this to PM if you like. I would rather give you too much information, than not enough.