My company does not require use of alternate airports. But if you are not careful they will consider them. For example if I say New York they will choose either JFK or LGA. If I say LaGuardia they will only consider LGA.

For personal travel, I have travelled:

60 mins to Youngstown
90 mins to Akron
120 mins to Cleveland
180 mins to Columbus

for cheaper fares It helps that I have a lease that's almost up but wayyyy underneath the miles I have already paid for.