There are a ton of varieties of playhouse out there. Some more complex and some very simple. Some very cheap and some VERY expensive. In the medium-price range the Naturally Playful Welcome House is perfect. It is sizable (adults can fit in), well-made, nice to look at (many of these playhouses are not appealing to the eye), and has all the key things adults/kids want in functionality. Door? check. Lots of windows? check. Kitchen? check. Table? check. SKYLIGHT? check. The only thing that is missing in my opinion is a bench.
This is available at Step 2 for $499 plus $29.99 shipping – this is the best deal I could find. It also comes with a double play-all-in-one sports trainer ($99 value). However the Step 2 site only has the one with the half-door and Amazon.com has a full door and no sports trainer for about $150 more.
All you will need is a welcome mat to be home.