If you're having a new home built, you might look forward to the children all having their own rooms, to entertaining in your new home, and to being able to store all your "stuff." However, while many homes are built to accommodate that need for more space, you may want to talk to your homebuilder about downsizing your plans, at least for some rooms, as an oversized home means more money for utilities, more time to clean, and more repairs and maintenance. To ensure your home is the size you want without having to sacrifice storage or privacy for anyone, note a few areas of the home where you might cut back on the space you think you need.
How often will you actually use a formal dining room? If you're like many families, you would probably rarely use that space, if at all, as even holiday dinners can be enjoyed in a dining nook, or in a dining area that is attached to the family room. You may find that a formal dining room becomes wasted space, so consider foregoing this room, or downsizing it for a hobby room, children's playroom, and the like.
Having a spa tub in your master bathroom may seem like a good idea; however, as with the dining room, ask yourself how often you would actually use that tub throughout the year. If you're like many people, you simply don't have the time to soak in a tub on a regular basis. Rather than including it in your new home plans, consider creating a walk-in shower with steam or added showerheads, for a more luxurious shower experience that doesn't require the added space of an oversized tub.
It can be nice to have a private place for reading your favourite novel, but many people today read from their smart phone or tablet, rather than actual books. Rather than assuming you need a large room with lots of shelves, consider a library with a comfortable seating area, and with just enough shelving for the few physical books you'll want to collect.
A roomy garage is good for keeping the cars safe and for locking up your lawn care equipment and tools. However, an overly large garage will cut into your side yard or backyard, and reduce the space you have for enjoying the outdoors. Consider storage options on the garage ceiling and along its walls, to maximize the space in the garage without making it too big and too imposing.