Going through an agent will not necessarily be cheaper. They will *include* booking fees in the price quoted and be restricted in the seats they have to offer. I have found them to be always more expensive.

Callling the airline directly means paying a booking fee per person and child AND a hefty bill for the phone call to a special billed number. Singapore Air charges 50 raps a minute!

Booking online - this is an endless frustration for me at the minute. Booking stopovers bumps up the price of the ticket to a crazy amount and you can't seem to make the same booking online as the one you got from the airline over the phone.