Go out on pretty days. Stay off sea sickness producing waters. Use a marina or campground with showers for the first overnighter. Use grinders-submarines-heros for meals. Soups are good. Cola drinks also settle tummys. Ginger snaps for snacks. Let everybody drive.
Once I cured a case of incipent seasickness by having her (17 yrs.old) take the wheel into smoother water. One is less likley to get sick while steering. Stay within sight of land for a while. It's comforting for a beginner. Anxieties about being lost at sea with her whole family aboard isn't good for Mom.Taking turns (watches) will keep the kids interested. Go someplace. Having a goal is easier for kids.
For me there is an inexpensive campground with slips about six hours away on the other side of a lock. That has always been a good first trip for my crew. Momma is much happier after a hot shower. Kids like campgrounds generally, and were quite thrilled with the lock and dam.
Seafarer 29 KCB