American Airlines has round-trip flights from Seattle (SEA) to Nashville, Kansas City, Tampa, Detroit (BNA, MCI, TPA, DTW) for $191 with a connection. Dates vary, see the example dates section on our website: Most flights are between March and June or August and October. Mostly Tue, Wed, Sat.
A Carry-on bag and also a personal item is allowed for free on American. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.