If you want to check your bags, don't you HAVE to be there at latest 60 mins before your flight? (don't they close the bag check in?)
With flights, DH hates messing around. It's easy to run late and it drives him nuts. The worst lines we have seen at our airport has been for the last two 6am flights. Normally we fly late afternoon/evening and never have an issue. The morning flights have been crazy long lineups.
Say you get there 90 mins early...
15 mins to check bags/get through security (if line is short)
30 mins to get breakfast/meal
15 mins to wait for boarding time (your buffer time)
30 mins to board the flight (20 mins for some airlines)
Flight departs
That adds up to 90 mins before your flight.
While we have done the 60 mins before, we find 90 mins to be just enough time to go through everything at a relaxed pace.
We always eat at the airport now. Adds to our buffer time (if something happens like traffic or extra long lines or whatever), we can always skip our meal (or takeout to eat on the plane).