For new homes, no difference between hardwood and tiles in terms of cost. If you want hardwood in your kitchen, simply ask the builder to change it from tiles to hardwood at no cost. For look, it just the fab now to have hardwood floor in the kitchen, when it's out of fab after a few years, it might look weired to have a hardwood floor in the kitchen, you dont' know right. play safe, and like most others said, it's lot more practical to have tiles wheater with/out kids.