I booked our March 12-20 trip just last week. Roundtrip non-stop flight is $286 per person for my family of 5 coming from the Twin Cities. Although my off-site resort is booked for the 3/13 to 3/20, I will save $650 by flying late on 3/12 versus flying out late on 3/13 as I originally planned. Since I'll be in Orlando a day early, I will rent a cheapy motel room near the airport for $110 (they have free airport shuttle to pick us up

), and then take the free shuttle back to the airport in the morning to pick up the rental SUV. This will actually give us an extra full day in Orlando as well, so BONUS!!!
Here's how I shopped for flight:
-I used the common sites like orbitz, travelocity, cheapflights, etc... to look for the cheapest NS flights because I have an almost 3 year old DS and do not want to deal with a transfer.
-Once I see which airline offers the cheapest flight, I will go to that airline's direct site to double check the rate. Try looking at RT and one ways. Booking direct will usually cost less in fees and should help you a little more in case you have issues later on, i.e. making changes. It should also let you choose your seats.
-Be open to taking different carriers. We're flying down on Airtran because their departure flight time worked best for us and was the cheapest. We're coming home on Northwest for the same reasons.
-Be flexible. Flights generally get more expensive laster in the week Thurs, Fri, Sat and are cheaper on Monday-Wed. So if you can swing leaving on a Tuesday or Wednesday, it could save you some money. You'll have to decided whether or not you want your kids to miss additional school days. For $500+ saved, my older boys are gonna miss 2 days versus 1 as originally planned.