16fter with 2 adults and 2 kids will be very tight. I did it with a 17ft for a season but one kid was a baby and in the car seat (with PFD) most of the time and we only cruised, no fishing. You will be hard pressed to bring any fishing gear and do fishing on the boat with 4.
For just cruising I would say 18ft would be minimum size for 4. Bring all the gear for the kids, food etc and room for fishing gear and you will be able to move around each other no problem.
For BOQ it is not nearly as rough as the big lake but you will still definitely want a boat with a deep V type hull. This will give you stability in the water in those choppy days and as many in that area know boat safety is very key. Two experienced anglers have died in the last year being out in smaller boats when the weather came up quickly on them. Another sank a boat warrantied to be unsinkable.
Not trying to scare you, but safety is key and you do not want to be out with your whole family and get into a sketchy spot.
Some things to think about
1) How much will you trailer the boat? Will you ever get a slip?
2) How far will you trailer?
3) Will you ever head to the big lake? Salmon, etc. Primetime area for fishing in the summer and great family adventure
4) Will you ever be fishing early and late in the seasons when water is very cold?
For this type of water I personally would recommend around 20ft boat. As I said, I used to run a 17ft and have gone up to a 23ft center console. It isn't ideal necessarily for family outings but it is mainly for fishing. I am currently working on some additions that will make it more family friendly. But we do go out as a family regularly in it (2 adults, 2 kids) and take other familes with us (4 adults, 6 kids sometimes). It is a great time but I do not trailer the boat, I keep it in the water from ice out to December. I picked it up from thehulltruth.com forum. This is the best place to find big water boats in my opinion. Best pricing, catch is you have to import it from the US (very simple, can help if you want). Other more local spots for big water boats is Lake Ontario United forum.
Good luck, PM if you would like more specific info to this area.