that's the problem with hotwire or priceline for airfare - you get the worst times with the worst layovers/connections - it really eats at the vacation imho (the last flight out of the night + the first flight out on returning)
have you tried kayak.com? (they dont use southwest, so if that's an option to drive to an airport with southwest, check their lowfare calculator - my friend is joining us in Ft Myers due to that, Sat and Sun flights were twice (or more) than the Mon to Mon flight she got! (spring break - $456 vs $99!)
good luck!