Amazing stuff. What a pure criminal mind. Personally never really liked visiting in a hotel although had a few memorable ones back in the day. My strategy if I knew the location in advance was to arrive early and head to the bar and chill, blend in as you say. You can discover the lie of the land this way and at least have a good idea how your going to get to your destination.
In most hotels cleaning is finished by early afternoon although staff may still be wandering around the place later in the day. Lifts with a security block can be a problem but you can usually, pre Covid anyway, sneak in with a crowd. In general a busy hotel is not a problem you will not usually be noticed. However, visiting a premises in which nothing much is happening you are always likely to draw attention to yourself.