Space for a bunkbed
An extra thing you might consider if you only have 1 kid or if your son or daughter are not going to be sharing bed rooms is to get a bunkbed with a desk underneath. This is a great way to economise on room, more so if you have a kid that is going off to the first grade soon or is already in the first grade and is will have to spend time doing homework every day. If you are not going to purchase a desk for the room, you could always get a pull out futon as the bunk beneath, giving your kid 1 small bed above and then a bigger sofabed down below. This is really fantastic if your children like to play xbox games or lounge around, because this gives them their own particular space to do that.