Langley B.C. to Grimsby, ON and return the past 6 summers, with the last two in my 2011 JK Sport 2door. I drive via the USA though, as it saves time/money with many more places to eat and shower. I have done the CDN trip twice before, but living in a border town, I usually save ~ $19 per tank with every fill-up (Hate to say it, but I have never filled-up my JK in Canada).
In 2011 I spent $887.50 USD in fuel for the return trip, and $936.71 USD in 2012 (The Jeep was loaded with 4 of us and ~ 150-200/lbs of gear).
One way is ~ 4402, with last summer’s trip 10,379km total for the JK.
Coming home I cross over the Peace Bridge. Then thru NY/PA/OH/IN and into Illinois. Chicago traffic is 90% just plain crazy and I go south of the city and head over to Iowa. Just before Omaha NB, I start heading north into South Dakota. West bound thru SD/WY/MO and the tip of Idaho. Then just 8 hours left over to Seattle and North to home. I have made some alterations in the past, and have driven thru Wisconsin and Minnesota before, with this last summer straight thru westbound into Nebraska/bottom end of Wyoming/ Utah and Oregon.
Summer 2012 we took two vehicles and left Buffalo ~ Noon on Thursday and was back in Langley on Sunday ~ 2:30pm (3 adults and 6 kids). The year before though, I left on a Wednesday ~ Noon in Buffalo and was back at home in Langley ~ 2:00am Friday night/Sat morning. Usually just drive ~ 60-65 miles per hour, and just sleep in the JK and shower at truck stops.
Hopefully this helps, and if you have any other questions - go ahead and ask away. I have tried to add both Eastbound and Westbound driving logs with the post.