I work for a Fortune 100 Company, the only extra duties we have beside flight related duties are some Jepps. We have several World Jepp Sets and each pilot gets a section that he keeps up. We don't have to come in on our days off to do this, it is done at the beginning or tail end of your trip (but since the Jepps only update every 2 weeks, it isn't very often)
As far as picking FBO's, making hotel or rental car arrangements, our Dispatch handles all of that. On the road the crew takes care of ordering the catering, fuel and any aircraft services that might be required. When we get back home, we do the paperwork and that is about it...
I have to agree with the other fellow, if you boss makes you come in on your days off and do non-job related duties (sales calls, product support, wash the plane, etc...) I would look for another job (unless of course you agreed to these duties when you took the job)
Good Luck to all and fly safe!
Falcon Capt.