Of course they don't want hookers hanging out in their lobby but this is not what this post is about.
A guest bringing a hooker through the lobby to their room is not the same as hookers hanging out in their lobby.
If a guest at a 5 star hotel, paying the large 5 star room price, chooses to bring a guest to their room, the hotel is not going to be concerned about.
There is no way a branch of western international corporation like Hyatt is going to discriminate based on gender identification. Don't worry about it. If they do, just start to dial their international help line.
If anyone is wandering around Chiang Mai looking for spicy salad check it out. I doubt it will be there long as they go back to work in the cabarets soon.
I stayed at that Hyatt Regency in October last year. Very nice hotel! Check out the Spectrum Rooftop bar on the top floors. Very nice.
i was only there for 1 night and did not bring any guests in but I have stayed at the Grand Hyatt hotel many times and never had problems with bringing guests in (both GG and LB). During the days no problems, just up the elevators and to the room. At night time there were security at the elevators asking you to check your guest in at the front desk before you go to your room. This is best for you own security.
Being part of the Hyatt group (and same with most 5 star hotels in Bangkok), i would say it would be same policy at the Hyatt Regency.
There is a door into the Hyatt Regency straight off Sukhumvit Road and there is always a doorman who opens that door (day and night), so I am sure if you bring a guest, he would ask you to check them in. The main entrance is to the side where a taxi would drop you off and you walk straight past the reception desks so unless they super busy I'm sure they may ask you to check your guest in.
There are a few freelancers (both girls and ladyboys) that hang out on Sukhumvit right out the front of the Hyatt Regency. I checked them out but a bit rough for my liking.