Also be aware that the speed of check-in varies by airport.

A week after the bombing, I arrived at GRR two hours before departure and spent one hour and 45 minutes reading a book. With NWA's e-ticket kiosks, it literally only took three minutes to check-in with luggage.

I'm sure that you don't need to arrive at smaller airports two hours in advance. On the flipside, I read that someone got to Baltimore at 4 a.m. and barely made his 7:30 a.m. flight. Reason: The airport is a madhouse because it's taking a lot of National's traffic.