What route do you travel the most?
Couch to the fridge. 
CYDF to CYUL if you mean by airplane.
KMSP-KCLT on US Airways. All for connections in Charlotte.
OAK/LAX, almost exclusively on SWA.
CAK (or CLE) to MCO. My in-laws have a cottage (glorified trailer, actually) in Clermont.
BNA-ATL on DL, mainly when flying internationally.
STL/DEN
STL/MCO
STL/BWI
RVS-2V1
RVS-DTN
TRI-CLT
FLL-CLT
FLL-PHL
Mostly for connections
HNL to ATL Always on my favorite aircraft :]
When I was really flying a lot, I flew SVG/OSL R/T as often as three times a week for more than four years. It was about 40 minutes by air, but 10 hours by road. In the US, my most frequent routes were KLAX/KDFW and KDAL/KHOU.
I don’t fly much these days.
MCO-MHT/BOS
DEN/PHX
PHX/TUS
DEN/TUS
United and SOuthwest Airlines
MEM-DCA
MEM-DTW for the connections
both on Northwest
KACY-KTPA
Spirit Airlines ((thee bestt)) 
MDT/PHL/BWI to PIT.
The 40 minute flight beats the crap out of the 4+ hour drive…
MDT/PHL/BWI to PIT.
The 40 minute flight beats the crap out of the 4+ hour drive…
SAN-PHX.
I could probably fly J18 in my sleep by now 8)
CMH-BDL, once every three weeks
CMH-PDX, usually via MSP, on occasion via CVG. Once via SLC - never again if I can help it= 
- 2500 miles on a regional jet is numbing.