direct airfare from Ottawa to Orlando is a beautiful but rare bird - usually only when heavy traffic time (march break, etc.). Sometimes AC will offer it, but they'll change their times, minds just as often. Sometimes westjet offers it - it's hit or miss when; although you can search their pricing engine easily enough.It really depends what season you're looking to go. ;
With wee ones, if direct flights are important, you might want to drive to Montreal (2hrs) or Toronto (4hrs) to get charters - Transat, Noli from YUL esp. SWG from YYZ or YUL. ; Course, there are scads of direct options from Toronto or Buffalo. SYR is closer to YOW, and it's possible, but it's 3hr drive w/o border consideration, and it's hit or miss whether or not you can get great price jet blue, etc. Unless you want to spend time driving, dealing with border, parking to pay while away and/or ; hotel stay too; you might just want to consider just booking the hopper flight and preparing as best you can. ;
You're not going to do much better with air from YOW than $500 pp at the best of times, with or without that rare and beautiful direct bird, so you have to decide how much time and energy you want to invest to save that $100. Everyone's vacation time and money are precious items, of course, but believe me - Ottawa ain't the easiest town to get out of!