The Palms put up a congratulatory shout-out to Paris on their marquee this week in honor of her recent engagement to Chris Zylka ... and also plans to gift her a piece of its iconic sign when it gets replaced later this year, as part of a $485 mil property renovation.

So, why all the love? Well, Hilton's been with the hotel and casino since day 1 -- she opened it in 2001 while wearing a million-dollar dress made of casino chips.

We're told because Paris is part of Palms' history ... Palms wanted part of its history to be with her. Oh, and it says if she needs a place to celebrate her bachelorette party ... "our door is always open for you."