Did you say family of 6? All at once? 25% ocean?
No way you want a jon boat.
Assuming you have kids, the freeboard is *way* too low. I switched to a higher side/higher freeboard boat and I'm much more comfortable with the kids in it.
Also, there is no boat for all situations. Don't underestimate the salt and the Fraser - the water can get rough and with little freeboard and no V, you will be hurting and scared.
Do you want to fish the bigger lakes or only the small ones? The bigger ones like Pitt, Stave and Harrison can get very rough. Even Alouette would be no fun in a jonboat.
Not sure why you want a new aluminum boat - those are the ideal boats to buy used, and you can get a lot more boat that way.
If you don't mind getting a bit wet and you're just going out and back (without beaching and exploring), consider a bigger inflatable from someone like seabright. At least it is very seaworthy for its size.
I had a 16ft Lund SSV that was pretty good for water around here, but I still found the freeboard low. It was seaworthy though, but not terribly seakindly. I agree with the beam comment above - the more beam the better. 78" is pretty marginal, especially if you have kids aboard.