Just seeing this thread so hopefully you haven't gone but I will include my favorite spots to go.
I moved from Savannah 3 years ago but miss the area and boated those waters over 10 years. I had my SX210 stored in Thunderbolt so based most of these trips out of there. They do have a public boat ramp in next to that marina if interested as could cut down commute.
I agree with all of Elliot's tips above. Driving to different ramps may better for your however time on boat was always more enjoyable then fighting traffic getting to HHI even if it was 15 mile water trip for example.
Not to insult any ones intelligence or experience on Coastal water but I will share my personal lessons learned.
1. Vessel inspections-USCG Aux host free inspection almost every weekend at specific locations. Look them up in interested. You get a window sticker. With that I was rarely boarder by DNR or USCG. Without it or on friends boats being boarded for safety checks was guaranteed to happen on the weekends while cruising. I boated with a different crowd before kids though.
2. Water visibility of hazards. Follow another boat in to access best sand bar spots. If you touch don't assume its sand. You may get rashed but never jump off boat till you verify depth or rule out oysters. I still wear shoes to this day on any boat due to jumping on an oyster bed in Wassaw Sound.
3. Big Tidal swings-Use bigger anchor with chain. (Towboat US and Sea Tow is a great piece of mind)
-Stick to the outside of all turns if navigating any of the creeks or follow a boat. You will notice people may leave parts of the sand bar. Don't be the last boat.
4. Coastal and Southern boat ramp etiquette is much different based on my experience from people the more North and inland you go. Be prepared to dip the boat completely ready and loaded then circle back to pick up your driver specifically on weekends.
Favorite spots ranked:
1. Daufuskie Island (13 miles from thunderbolt by intracoastal) An little bit longer trip from Butterbean bc of the no wake zones
-Bloody point sandbar on southern tip is island
-Freeport Marina-restaurant and live music. Best boating atmosphere in the area. Would go almost every weekend and that was when gas $ was high
2. Tybee Island
-Sandbar on southern point is a favorite
-Hidden sand bar on Little Tybee just south of it
-Dock at AJ's, CoCo's Grille or Crab shack depending on tides
3. Wassaw sound sand bar (depending on winds with go to north side of sound or south side, inland of the fort ruins
4. Thunderbolt and surrounding area. See yachts at Thunderbolt Marine.
-Water sports-stick to Skidaway and Wilmington Rivers. Grab a drink at Cheers to You.
5. Savannah River Cruising-River St and to see the port. Use houlihan boat ramp- But Wake from passing container ships are always bigger then they look.
-Search for Megalodon shark teeth closer to Fort Pulaski. I usually found at least 1 per visit. Finding 4 during 1 walk had been my record.
6. HHI longer trip but there is plenty to see
7. St Cats sand bar-That 20 mile + trip from butter bean but if feeling adventurous there are also Lemurs running around on that island. Only made that trip in bigger CC's but still doable in the Intracoastal.
If you need any more specifics I can share through email.
Enjoy and safe boating
-Jay