I know a lot of our hobby activities take place in hotels but for the sake of this question let's not think hotel.

Couches are uncomfortable, got a BJ while driving once and almost killed myself and the lady, too old to stand her up against a wall, outside has too many variables, weather, bugs etc.  I'll stick to a nice comfortable bed thank you.

OMG!! What a great question 😈
Over my many years in this crazy hobby!

Besides beachfront,cruise ships, pool side, I agree with Melissa, anyplace outdoors. Years ago boat sex on the river back home was always erotic or stopping along the road on one of my motorcycles was terrifying and and intense at the same time! And yes road head including flashing and mutual masturbation was a great way to make a perfect weekend.

I have snuck up on a hotel roof at the beach when nobidy else is there late at night.  
As I was getting some great oral sex in a lounge chair I opened my eyes and seen people looking out their hotel windows down at us which just made it hotter. ....

There are numerous places that I've dreamed about getting physical with a provider. Oh where do I start:
On a Pool table
On a Kitchen Countertop  
In a Shower
In a Bathtub
In a Jacuzzi/hot tub
In a Pool
On a Boat dock
On a Boat
On a private jet (Aka joining the mile high club)
Inside a Movie theatre
Inside the private room at a Gentlemans club
In the back of a limo
On a beach  
On a golf course  
In an elevator....
There's a lot I wish to do.

It could be a lake, a river, or the open sea! As long as it's not a canoe; They tend to flip over too easily LOL!
Being on a boat in the water has a special way of seducing me to get naked!!

On a tractor...ducked off in a narrow passageway in a mall or or a city street

Back when the SO was more adventuresome, we did it in the woods, in a tent with other people (who were hopefully sleeping), BJ/handjob while driving (very intense), outside in the hotel hot tub.  

My lil country gal, at the time, prior to PFP, would tax my endurance to withhold the candy from her before arriving at the apt., and, it was all I could do to even hold it on the road with that lil cutie bobbing up and down for all she was worth on Johnson;P~~~ She was a treasure that I let slip away due to my wander lust(  Lordy, I sure hope she has had a good life) Then, there was the kitchen table for sum sumptuous dining;P~~ One lil lady, after "pet shark" had been engorging himself for at least 30 mins, told me, ERR, "shark", when I (He!)tried to get on with it, to GO BACK, and keep doing what I(He!, dang it!) was doing, until Tommy Tongue was about to pass out(PFP this time, but, not a clock watcher at all), couches, walls, ottoman(large), and floor, in front of fireplaces, the firelight flickering off those boo full bodies was like being at a picnic with the main course done to perfection, making my mouth water, not to mention what it was doing to Johnson) "Happy Days;P~~~"