If you mean you're doing in-calls at a hotel, it doesn't really matter, so long as you've got something respectable to open the door in. Matching lingerie under a dress is a good option. Then I'd keep some civvy clothes to hand for when you want to pop out for food etc.

For packing and not taking up much space, jersey dresses are great as they don't need ironing, and can hug your figure nicely if you pick the right one.

You don't really need to "blend in" all sorts of people use hotels and walk around in all kinds of clothes from suits to casual clothing, if I have particular outfit requests like costumes obviously I'm not going to walk around in it, I'll get changed in the room when they arrive or when I get in their hotel room if I'm doing an outcall, but I just come to the hotel in cute casual clothes like I've at least made an effort to look nice even if I'm getting changed right away but they are just regular clothes so it's not like anyone cares.

Unless you're going to some fancy dinner or a wedding I don't believe dress codes exist.

I would suggest some classic  not too revealing dress. It always  works for me