I adore this theme for a twist on a housewarming party. I think most people would agree that there really is no place like home.
the color yellow is a must, incorporate it into your invitations
yellow floral arrangements all around the home and on your table scape
have kids? Let them dress up and break out your own ruby slippers
a rainbow array of sodas seem most fitting
don't forget dessert, these cupcakes on top of the witch are brilliant and how about animal crackers for the little munchkins (lions and tigers and bears...oh my)
I know I'm only skimming the surface here. However, one last thing I propose is drafting a map or blueprint of your new house. The reason being, guests will want the grand tour and although you are always the most gracious host, you might not be able to be the tour guide each and every time. So let them follow the yellow brick road (aka-that little map I told you about) and get acquainted with your new home on their own. Have fun with drafting the map and personalize it! Identify the rooms. You can label the kids play room "munchkin land" and if you have remodeled, add some before pictures, those are always fun to share. If you have plans to decorate, include your ideas or inspiration for those spaces. It is after all, a new home... share and ENJOY!
Images: Invitation via Invitation Consultants, Girls Dorothy Dress via Sew Dainty Boutique, Witch cupcakes via Kelly Sweet Rewards Rainbow of Sodas via Project Wedding, yellow brick road via Imprintables blog, Red Vintage Bow Shoes via Ruffled Blog, Yellow table via Once Wed.com