@Boomrocker: That seems like a good start, write it up and we'll see how it goes.
Presumably, the first floor or so is standard castle and dungeon fare, right? Fieri, being largely outclassed and unwilling to stray too far from the entrance, won't get to the weird stuff until she has a reliable customer base (i.e. the rest of the party).
Fieri heard of the castle's wealth, popularity, and spectacular ease of looting from someone who has experienced it firsthand, and recognized the mercantile opportunity in the making.
Inferring and describing the architecture and decorations of a long-defunct castle is child's play, and most likely can't impact the lower levels in any meaningful way. Plenty of mortar, plenty of dust, plenty of rotten wood and maybe one or two goblins. Fieri's planning on making her immediate area as safe as possible, and immediately going to set up a storefront. At the cutting edge of mercantilism, there's no way for her to lose in today's cutthroat economy!
@Boomrocker: While it does make sense, I would have liked if you asked before putting him in the same group to start with as Tanya. The only reason Sophia's there is because it was discussed beforehand.