That is a long visit so you want to show around $20k just for the trip, $5-10K for airfare plus additional for savings. You need to show funds, travel history and ties to home country. You want to show that you are not spending all your savings for a visit. Where do you live?
Another way to look at is that for a family of four to travel to Canada will cost you $8 to $10,000 in air fare depending on which country you are coming from. If you have funds of $12,000 that would mean that you are spending around 80% of your life savings on a 30-day trip to Canada. That would not be a wise choice. So your funds would have to be sufficiently higher to cover your expenses, air fare and then have enough left over that this trip would not exhaust your life savings.
Where are you planning on visiting? Cost out the week including accommodations, food, airfare and then add an additional $5-10k to show that you are not spending all your money. Funds must be from your own personal accounts.