This may sound a bit obvious, but seriously, are you planning to do a series of trips? Could they be combined? Is there a fellow colleague who is travelling in that area who could attend your meeting instead?
With careful planning, the number of trips and hence time out of the office could be reduced, not only cutting your travel expenditure but increasing staff productivity too.
Some ‘full fares’ are based on maximum permitted mileage, thus enabling the traveller to stop en route. So to combine meetings in Singapore and Sydney by using a full fare ticket to Sydney would be considerably cheaper than planning two separate itineraries.