There are many factors involved with pricing such a project. If your house is a ranch home with one level, it will cost more than a house with an unfinished partial second story, like a Cape Cod house. The pricing also depends on how many rooms and the square footage of the rooms you wish to add, which may be limited based on the size of your home.
The bathroom price depends on the materials you want to use; for example, a simple small resin shower or a shower/tub combination is less expensive and easier to install than tile. A window and/or skylight in the bathroom adds to the cost, but most people wouldn't dream of adding a room without one.
Generally, my personal experience in New Jersey is that to add a Cape Cod (dormer addition with 2 bedrooms (about 11' x 16' and 14' x 14') and an 8' x 10' tile bathroom with shower over tub to a Cape Cod house costs at least $80,000, or about $175 per square foot.
It is important to consult a professional for estimates and be sure to check references-- or use Angie's List!
Source: Sue in Morris County, Homeowner of 6 homes over 25 years