I usually calculate 1-2 rolls/day/camera. Depending on the destination - that works out to about 30-40 rolls for a 2 week trip.
I also know that some places are "film heavy", big cities like N.Y,Paris, Tokyo can be up to 8-10 rolls a day!
I "de-can" the film and put it in freezer bags. First in smaller Zip-Loc bags (10 rolls in each) and these then go into a bigger bag. This way I can grab a 10 roll bag, stick it in the jacket/vest pocket in the morning - shoot away happily and re-stock in the evening. I also bring an additional bigger Zip Loc bag for exposed film. I hate having to dig through a mixed bag with exposed and un-exposed film.
You can also tape filmcontainers "back to back" so you can carry 4-5 of these in a vest pocket. Sometimes you are spending a lot of time in cars or crowded airplane seats and you can squeeze loose rolls in the pocket enough to pop end-caps.
As a rule I never check luggage. Film, cameras etc goes in first and if there is space, clothing. I rather run out of shirts,socks etc - which is easy to find almost everywhere - than film.
Two cameras in the small Brady bag, maybe a third lens and one back-up M2 with a 35 or 40 mm in the bigger shoulder bag.
Addendum: You cant have too much film along! Add the cost of the trip, lodging, food etc - film cost is trivial.