Just going to add my two cents as well! Welcome to the boards and feel free to ask as many questions as you'd like!!
I agree with many of the other posters about flying out of Buffalo on SW! If you're concerned about the cost to add a night in a hotel in Buffalo, look at taking a later non-stop flight and driving across the border in the morning. I have found this option much less stressful actually, and then all I worry about is getting down there and getting settled and checking out the resort that first night. No pressure to do a park because it doesn't make sense. The only thing I would definitely recommend is adding the earlybird check-in option to your flights. Because your kids are older than 4, you will not have the option to pre-board with the family group after the A boarding passes, and lately there has been less of a chance of getting the A boarding group even if you jump on the check-in right at the 24 hr mark. Yes, it is $10 per ticket, each way, but it does give you peace of mind that check-in is taken care of on the way down, and more importantly on the way home, letting you relax 24 hrs before heading home instead of having to find a computer while you're down there!
The other thing I would add is really do your research on the free dining offer. You will be paying rack rate for the room in this case. Take a look at the restaurant menus (allears.net or wdwinfo.com) and prices and get a feel for what your family will eat and how often. Although I have only done the full dining plan as opposed to the quick service, I have found it to be way too much food, and really we were only breaking even or saving a couple of dollars. I have found that doing each piece (room, dining, tickets) seperately and getting the best deals on each has saved way more money. I would advise trying to book it yourself by calling Disney directly and asking for room only discounts (if you have CAA/
AAA, you can ask Disney if there is any discounted rooms using that...it's always my standby until I find something better).
For tickets I would recommend looking at undercovertourist.com (I have ordered from them several times...love their service and speed!!!!). Really weigh whether you will use the "hopper" option. I used to get it, and found with little kids it is just too much physical effort to hop all over the place. I plan out which park is the best on which day and stick to it, planning dining and breaks around that park.
To save on food costs, I do rent a car and stop at
Walmart on the way to the hotel and stock up on bottled water, snacks, cereal or other breakfast foods so that I'm not paying through the nose for that in the parks! I also tend to buy a lot of my souvenirs at Walmart too (they stock a lot of Disney items at that location...t-shirts, pjs, stuffed animals, trinkets, etc), yes they aren't official park merchandise, but my kids don't know the difference! There is also an official Disney outlet store in the Prime Outlet mall that carries official stuff sometimes at great prices, especially pins!
Another option for souvenirs is to shop at the
Disney store at home before you go, or order online from disneyshopping.com (outlet sometimes has awesome deals) and have it shipped to your resort (I have done this a LOT and can tell you step by step how to do it if you want. Don't ship to Canada as the cost is exorbitant!)
For rental car savings, use mousesavers.com for discount codes. I like Alamo personally. You also get free parking at the parks if you stay on site (this is a significant daily cost if you aren't staying on site!). If you just can't justify the car, you can of course rely on Magical Express to/from the airport if you're staying on site, and then do the buses/monorail/boats.
Well, that's my thoughts! Hope it helps! Enjoy your trip!!