My flying was all over the place this year.
Most frequent flight was UA 152, SFO-ORD (the 6pm-ish departure). SFO-ORD was also my most frequent route, did it 6x.
Runners up were:
EUG-SFO - 4x
ORD-LAX - 4x
ORD-SAN - 4x
About 120k BIS miles this year. I'm beat!