Well either Shizuka or Cat would be a problem as there are not many beds available. Remember it would be another hotel or share a room with double bed. Neither Amy or MC would let either of those sleep alone in a hotel, so considering MC has spent not nearly enough time with Amy yet I hope indeed for Shawna or other girl that will have her own thing to do during trip and might then have a bigger part after trip or real best girl Molly for a more humorous instead of lewd scene.
If Amy path will be slow buildup I could see some interlude with MC having some fun with Shawna or Jo in Paris though to add an extra scene though Amy's boss would likely be the first suspect for such a scene imo.
