kyles - I'll second that using cloth in the tropics is very effective. I'm in Cairns too, and I initially thought the same as you, that cloth would contribute to nappy rash or over-heating here, but have been using cloth successfully. There seems to be quite a high proportion of cloth users up here - as an example, about 60% of my mum's group use cloth full time. There are many good stay-dry fabrics and this helps immensely. Not trying to convince you away from using sposies if there are other reasons that you'd prefer to use them, but just letting you know that cloth can be used successfully in the tropics in case that it's the only reason that you've decided not to.

Another thing to think about with a nappy bag is how you think you'll be getting around. Will you be driving a lot, or walking/using public transport, or predominately using a pram or using a baby carrier. Will the trips away from home be mostly short, or will you be away from the house for an entire day (for example).

If you mostly drive, and can leave the bag in the car, or clip it to the pram, or won't have to carry it for extended periods, then a 'kitchen sink' type bag is an option - the type of bag that fits everything - but remember that 'everything' will weigh a ton, so you can just throw a nappy, some wipes etc into your handbag or a smaller bag when you duck into the shops and leave the main bag in the car. I have an Isoki - it is a typical kitchen sink bag - huge, great quality, but quite uncomfortable to actually carry.

If you plan to be out and about a lot, or to use a baby carrier more than a pram, a messenger type bag or back-pack style can be useful - something that is comfortable to carry, and not too heavy. Even though they are not specifically designed as nappy bags, Crumpler bags make great nappy bags if you are out and about alot or baby-wear. There are also some good WAHM bags, and the Onbag is a bag specifically designed to complement babywearing (a WAHM based in the UK). The pattern is available online if you sew, or she does custom orders.