Take the night crossing in North Sydney and book a cabin. That way if travelling with kids you have your own room.
I live on the West Coast in Corner Brook and IMO there is so much you can do just on the West Coast alone. If you want a good party head to St. John's and George Street but if you are taking family, I recommend staying on West Coast.
Book a chalet at Humber Valley Resort
humbervalleyresort.ca
Drive to Rocky Harbour and take the boat tour:
https://bontours.ca/tour-item/western-brook-pond/
Check out Woody Point and Trout River:
https://townoftroutriver.com/
Hike Gros Morne:
https://parks.canada.ca/pn-np/nl/grosmorne
*note the boat tour I mention above takes you to the bottom of the fjord where you see the water, it's pretty neat.
Go Zip Lining at Marble Mountain (2nd highest vertical drop in all of Canada I believe)
https://marbleziptours.com/
SOOOOOO much to do just on the West Coast Corner Brook / Deer Lake area.