[Butch Cassidy Slept Here]

If the OP has the opportunity to get a full refund from Delta, I would recommend the the connecting service, on Midwest or Continental, I referenced in my previous post. The non-stop Delta/Northwest flights, MSP - TPA, do not justify the aggravation the OP will probably endure if anything unexpected (on the part of Delta/Northwest) happens. For example, if there is bad weather in Minneapolis, and the flight can't take-off until the next day, will Delta/Northwest refuse to allow you to have your baggage (re-checking it the next day), thus holding your baggage hostage? Then there's the question of airport agents with an attitude. At a large airline these people can hide, and sometimes, even be protected. And, yes, that last statement COULD apply to Continental, except, again, one has the aforementioned compensating factor of a Houston connection (less chance of snow/ice).

PHX Flyer wrote...

Why would Sun Country not be a viable alternative?

For one thing Sun Country may still be in bankruptcy proceedings. I have yet to hear anyone characterize bankruptcy as a “morale booster” for airline staff. Also, it's my understanding Sun Country could be the originator of bad airline service like sardine class and unreliable schedules.