Hmm.. Not sure if you are asking how to prepare in the sense of the room, the ambiance, things to have on hand? Or if you are really asking what to expect? It's important to have agreed upon or understood boundaries and realistic expectations as you go into this or it may not be how you build it in your mind.
A lot of us have been there and there are many things to consider especially for your first one. You've taken the most important step in my opinion and that is your first is with someone you have spent time with before so you have some idea of how you get along which is good. That said, spending 1-2 hours with someone is still a hell of a lot different than spending the night.
Let's talk some basics though you are no rookie at this overall but like I once was a first timer for the overnight. In or out? My overnights have always been an out call so I was on the hook for some planning for the evening and the room environment.
Have you talked of your plans? Most ladies will require some public and private time for an extended or overnight. Do you know what she likes to eat or is she vegan or something of that nature? Have you researched food options if you aren't familiar with the area? How long is the overnight? For some ladies it's 8 hours, for some ladies it's 12, for some it's a range of time. What are your and her expectations for the evening? Many times this information can be found on her website if you don't already know. Dinner, drinks in, fun, sleep, fun in the morning and then roll out? Fun before, dinner, fun, sleep, maybe some fun in the morning? Does she have a sleep requirement regarding amount of sleep? Same room, different beds? May sound strange but some ladies do have that requirement.
These are a few things to have discussed prior to or at least have thought about and have some options from your perspective. I won't say it can't happen but it would be rare for the entire time to be spent behind closed doors non stop. I did have that happen once but it is not the normal thing nor what I had actually planned she just damn near killed me, bless her heart : ) Fortunately beverages and snacks aplenty were pre-planned so it all worked out well. Except for the fact that I didn't sleep at all and had to work almost 24 hours straight the next day. Ah but the memories, worth it all...
As for the room. Ambiance if any is up to you and the established boundaries you may have with the young lady already. I've got my things I do depending on the lady and our previous experiences, but that's me. What I enjoy is not necessarily what you may enjoy. I would highly recommend refreshments, un-opened beverage of course, plenty of water/refreshments and potentially even a few snacks for the evening in case you should work up an appetite. Reach out and see if she has a preference, little things add up to big things, just like the civvie world.
I'm sure others will add more and I'm sure I've probably forgotten a few things. I don't want to over complicate it and certainly you don't want to bombard the young lady with a thousand questions, but these hopefully give you the opportunity to do a little planning or maybe think of some things ahead of time instead of on the spot.
Other than that, relax and enjoy. My first was awesome, the 2nd was better, and it is what I do most of the time anymore. I don't get to do it as often maybe, but I truly enjoy it.
I'm pretty familiar with the Greensboro area so if you want or need any food recommendations let me know and I'll be happy to recommend a few options. Enjoy!