Summarize the following:
Open up some rooms so that you have more of an open plan space. Create a spacious feel to your home by knocking down a few walls. Discuss your options with an accredited contractor before making any drastic decisions. Make sure that you take into account which walls secure the foundation before making plans, and work around it. You can add an attractive pillar if it's secure enough and fits the character of your home. If you have an unfinished basement, consider finishing it and creating an extra room. This will always add value to a home, so the investment will be worth it. You can even keep it simple by just finishing the walls and carpeting the floor. Adding livable floor space to your home will almost always add value to the home. If you have an attic with usable space, you should maximize its potential and utilize the space whenever possible. Work around any existing ducts and machinery to maximize the area you can use for this project.  This might include finishing an unfinished attic (adding sheetrock and flooring) so that it creates an entirely new room in your home. Or you may just want to add insulation and partial flooring to your existing attic space so that it adds a separate storage option in your home.

Summary:
Create space. Finish your basement. Add insulation or finish the attic.