With the very little scanning I have done with milair (recently started, and no dedicated receiver to leave on all day), I've copied action on the following frequencies:
311.00 - lightning ops
235.1 - AR-200 Primary-Coastal
364.200 - NORAD
345.00 - Coast Guard Primary Ops
270.1 - ATIS
one of the tower freqs, forget which one
Also scan the nationwide CG channels, there are some very active ones VHF and a few UHF that pop up sometimes, but often encrypted