American Airlines has round-trip flights from Houston (IAH) to Chicago (ORD) for $97, NONSTOP. Flights October to April. Mostly on Tuesdays, Wednesdays, or Saturdays. Extended Weekends (SAT-TUE) available. Origin/Destination reversible.
Note: Carry-on bag is allowed for free on American Airlines. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.