I've been on a commuting contract for the past 7 years and this is my opinion on the matter: being away for 4-6 weeks at a time and commuting in coach will NOT be sustainable on the long run, most likely your family life will suffer in the process, you will need a set of days off every month to be able to make it sustainable on the long run, right now the two best commuting jobs available anywhere in the market are Air Japan, Korean......! These two jobs will give you 12 to 13 days at home (depending on where you commute from and if you are able to leave the last day of duty) and the commute is in business class. 6 weeks on and 2 weeks off (even 4 weeks on won't do, unless you get 4 weeks off afterwards) will not work on the long run....!
Good luck