After coming through the front door, which had been made to look like Platform 9 3/4, they went straight into Olivander's Wand Shop (the office) and after choosing their wands (which The Hubby cut from wooden decor sticks I found in the floral section of WalMart), the kids boarded the Hogwart's Express (which was in the front room.) The guests filled their favor bags from the trolley of candy and treats, and I printed out quotes from every Harry Potter book (from thereadables.tumblr.com), mounted them on cardstock, and they got to choose their favorite one to take home. The dining room with party food and drinks was the Great Hall and we hung mini-led candles from fishing line. The family room was the Common Room, and contained spell books to study from, while the television played Harry Potter and the Sorcerer's Stone. And finally, the back yard was the Quidditch Field (which thank goodness my adopted family plays every year at family reunions, so I just had to borrow theirs!)
We had loads of fun, and it really wasn't that much work as far as parties go!