Check Southwest first, then I head to Google flights which consolidates the best options from every airport within a radius you pick. Google flights do not include Southwest. Figure in luggage costs if not flying SW, unless you have the airline's branded credit card.
For example, I live 20 minutes north of Lexington, KY. The Cincinnati Airport is 55 minutes away and Louisville is an hour and 5 minutes. Those are my home airports. For Disney, I look at MCO first, then include Tampa, Melbourne, and Daytona (Sanford if Allegiant is an option). For our trip in April, flying to Tampa from Louisville and renting a car is saving us $300 over flying to Orlando, even including Frontier before bag costs. October 2017 had insanely cheap prices from Louisville to Melbourne($60ish), the return was on SW for around $100 out or Orlando. The one way car rental cost $65-we saved that on a grocery stop alone.