I definitely want Hotels EP. It could add in gambling, pool slide, pool bar, new ownable business/new way to vacay to other worlds, gift shops, new excursions.
I too wish for a Medieval world GP or EP. The kit is not enough haha. I would love if maybe it wasn't actually set in that time period just cause idk how well that would work on TS4. But it would still look like it was and offered all sorts of medieval gameplay such as a jousting or sword fighting skill with tournaments, a renaissance-type fair as a new calendar event, different medieval-type foods, clothing, and maybe a new crafting skill like sewing, welding, or maybe a glass blowing object that lets you make decor, usable perfume, etc like TS3 had.
Also more off-the-grid bath and kitchen items and a new blacksmith career would be cool too. Really what I want is just an amped up version of The Sims Medieval :D