Kel and I take two 2 kg bottles (infact they are possibly only 1.5 not sure now)
They are small any way. We use one with the 3 burner stove and a lighting pole / splitter to run the gas lantern (mind you its only a small lantern - but throws a LOT of light for just the two of us) at the same time. We get about 4 to 5 three night camping trips in before it needs to be refilled and we have another which we take for a second gas lantern which has never been refilled in the 12 months or so we have owned it.
A place I'd rather be...
Mitchel Road, Bomjinna. Central West Victoria (Jan '08)