Reasonable corporate travel policy
Are they hourly employees subject to overtime laws in your particular state/city? We often send staff to London and they spend the weekend in city -we save airfare costs and they get a weekend in London. As salaried staff we do not need to compensate "overtime" or provide additional time off as the UK visit is part of the job requirements.
Do you keep time sheets, pay overtime or give comp time to all travelers? it should be the same for all unless again subject to laws in my opinion. I'm a corporate travel manager and do HR for a small firm. while it is nice to give comp days for the long trip what if another traveler wanted that too and you said no? I think you end up in HR territory