Welcome skymutt and stayl13!
I would hold onto the miles unless they are near expiration. Do you ever fly out west from TPA? Delta (via SkyWest) has pretty good coverage to a lot of smaller airports out west which are normally expensive to fly to. I don't usually spend miles on domestic flights, but when I do I use them for trips to Montana. These flights are usually $400-500, maybe $350 if you catch a deal. So I consider them to be a good value for my miles. I would recommend saving your miles for a more expensive ticket.