I don’t see anything wrong with that. It’s no more or less “immoral” than the objectification of women and men as mere objects for emotional gratification. In the way you describe it, a man (or a woman) can see a woman (or a man) as an object that can be useful in fulfilling their sensual (that means sensed via touch, sight, hearing, tasting and smelling i.e. Physical) desires. In the way I am describing it, a man (or a woman) can see a woman (or a man) as an object that can be useful in fulfilling his/her emotional desires such as a desire to not feel lonely (aka desire for companionship), a desire to feel loved and cared about, a desire to for intellectual stimulation, a desire for (finanical) security.
As you describe it, people see people as sex objects, or objects to fulfill physical desires and as I describe it, people see people as objects to fulfill non-physical desires. Many people view the fulfillment of sensual/physical desires as immoral but view the fulfillment of the endless list of emotional desires (anything other than physical desires) as moral.
There is a double standard, and it shows in the term “sex object.” When a man wants a woman solely for the purpose of fulfilling his physical desires, he is said to be guilty of objectirication, of seeing her as a sex object. But when a man wants a woman for companionship, he is not accused of objectirfcation, of seeing her as a “companion object” which is what she actually is to him. It’s just a different desire (or set of desires) that the object (the woman) is fulfilling.
Anyway, I agree with you that it is not immoral If “both people want to have sex for the sake of personal pleasure.” And I agree with you that it is immoral for one to be deceitful to have his desires fulfilled. However, the desire for sexual pleasure is not the only desire that people use deceit in order to fulfill the desire.
So if you are just honest, and say “I am in vegas for a couple days, and think you’re hot and would love to fuck your brains out and have a lot of fun with you” and she says OK, then there is no problem. Even if she says no, and you just agree to kiss and have fun, you’ll have fun doing that, and she might (in other words, she will, if you’re a good kisser/lover) change her mind and and decide to fuck anyway.