I use orbitz.com to get an overall idea of what the rates are for my dates and times that I want. For the last couple of years, it's been Delta that's had the best times and rates. Also, they seem to be the only one offering a non-stop flight from Boston (Logan Airport) to Orlando. Another thing; for the airfare that I recently bought for our cruise next summer, Delta's own web site was $6. cheaper per ticket than what orbitz.com showed for Delta. I think it might be due to orbitz charging a fee or something.
I could fly southwest out of Providence, Rhode Island but the idea of waiting until 6 months prior and the idea of not having assigned seats does not interest me in the least. Also, the rates I've seen haven't been much lower, if at all, than what Delta's had.