Pictures! Also, books, lamps, plants, throw pillows & throws...
Pictures always give a homey feel. You can find frames from cheap to very expensive, ether way they add a warm and personal touch to the room. Don't forget to put them on the walls too. If you have artwork/writings from your children, those would be great to frame.
Lighting can make all the difference in the world from the placement, shade color/transparency and the type of light from the bulb (soft white, LED, cfl etc).
Books on a coffee table, side table and/or book shelves.
Plants are great if you are good with indoor plants (unfortunately, I am not).
If you can find throw pillows on sale, you make all the difference in a room especially if you are choosing a new color, shape, theme or style. A throw across the arm of a chair or couch is always cozy looking.
Paint always changes the feel of a room. You don't even have to paint all the walls, you could do an accent wall.
With any addition or change make your choices personal from the style to the shape. In other words, get what you (and your partner) like despite what you may think others will say/think.
Have fun!