Another thing to keep in mind is the WEATHER. You're flying in February. We fly from Massachusetts to FL every Feb, and have done so for the past 6 years. If there is dicey winter weather (snow, hail, freezing rain, etc) it can wreak havoc on flight operations all OVER, not just your own airport. Think about what happens if your flight gets cancelled. Do you want to be flying with Allegiant, with the very real possibility of there not being another flight for a day or two, with no guarantee of space for you. Or, do you want to be flying with Delta. Yes, they have their own set of issues, but they also have a much greater capacity, and ability to get you where you are going.
We were on Delta one year, during the 'Valentine's Day Storm'. It happened to also be President's Week, and the soonest Delta could get us to Florida was three days later. And to a different airport. If we had been flying on Allegiant, Spirit, Airbus or the like, I suspect our entire trip would have been canceled.
For me, the peace of mind is worth paying the extra to fly Delta.