This is going to depend a lot on what type of client you are and what type of provider she is. Are you going to fuck for 8-12 hours straight, can you? Is she a fucker or a sleeper? I think this is the biggest single piece of chemistry to get straightened out.
If you feel compelled to go on a date and/or bring a bottle of alcohol, and look forward to sexless cuddling, then you want a sleeper. If you expect to take refraction naps, for 30 min to an hour and go at it, and expect her to wake up and fuck, then get a fucker. Reviews help here, and you will need to feel her out in email and probably a phone call or two (if you're worried about personality, just hearing her voice can get you a lot of information). Personally, I send an email with a list of things we might get to, and I expect no reservations or refusals from the girl, if she's not into what I want to do, then I know I'm not down for 8 hours of paying her to enjoy herself. AND THIS IS THE KEY, she is a service provider (not a girl friend, that's why it's GFE and not GF), if YOU are having fun, then everything will be a success, so worry about you. If YOU have a great time, you may miss the money, but will be glad you spent it, and you will write a great review, win-win; if you worry about HER, then you run the risk of having an ok time, you may begrudge the money, and you may not recommend it. So PLAN your overnight, share your plan with her, and get comfortable that she is going to make it happen.
Both of my overnights were sight unseen, but both ladies had exceptional reviews. The first one was a half day, I told her I expected lots of "unnatural sex", dinner, and sight seeing, which she all agreed to. She was awesome, BUT she was a heavy sleeper, and sleep she did. No 4 am wake up fuckee/suckee in the dark, she slept till 9:30am! However, the two times we went at it were intense, I assure you, I got my money's worth, because I took care of ME. The second, was an 8ish hour show up at 9pm leave at 6am deal. She was all about getting my nut out, and she never hit REM sleep. Every time I woke from my dozing, she was on the stick (think 4 or 5 times). We slept with the lights on. Unfortunately, a miscommunication led to an upsell situation, which I was not prepared for, my fault, I didn't get specific enough. So my suggestion is to be specific.
And important to note, neither girl had native english, finding shit to talk about was not on the agenda; obviously the first date involved much more communication and she was fluent, but I was after fuckers, and I got fuckers (the sleeper made up for it when she was awake), and had a great time both times. I don't even miss my money! Personally, I think if you are a cuddler/bartender you have a more difficult situation, because that kind of chemistry and personality is harder to match with out a prior meeting/connection. Also, in that situation you won't be measuring success in acts completed, which I think makes it harder to decide if you regret the cost . . . I know I would have trouble paying for downtime, cause that's money I could have spent on another girl. I think it would help if there was something special about the provider (race, looks, kinkiness, flexibility, body type), at least then, if it is only an ok time, you can still tick something off your bucket list to make the event a win.
Practical advice: unless she has a special fuck lair (or you are in a dirty hotel) have her come to your hotel, it's cleaner and plenty of clean linens. Bring your phone and a charger so you can set an alarm to remind you to fuck (you don't want to really fall asleep and waste an opportunity). Bring a video camera, if she's ok with that. Bring porn, lots of porn and a computer to watch it on and an HDMI cable in case you can play it on the TV. Have her bring toys. Bring a sex position guide, and try some out; once you're on round three, it will take a while, might as well have fun trying out new positions (a guide is a helpful reminder). Get plenty of water and ice, you need to stay hydrated; seriously, not having enough liquid in you after round one means you may nut a single drop in round three. Don't overfill the tub, two people in a tub and all you really need is like two or three warm cups of water and the tub is full, keep the water level low.
Goodluck!