Jacuzzi
If doing the "romantic bath" idea in a bathtub is a great opportunity to sensually enjoy as a couple, doing it in a jacuzzi allows the same with the added benefit of having more space to unleash your playful spirit.
Since almost no one has one of these at home, you need to know what resources are available to you so you don't have to miss out on trying one:
On one hand, any reputable gym has one or more, although unfortunately, they can't be rented for personal use.
Another option could be a spa, but we'll likely encounter the same problem as before. It's unlikely they'll let us rent one.
In this regard, the most recommended option is to look for hotels with rooms that have a jacuzzi. Obviously, the price will be significantly higher than a regular room, but even so, it's a treat that's within reach of most budgets. A word of warning: ask the hotel what the jacuzzi is like before booking the room, as some hotels use misleading advertising when they advertise a jacuzzi when what they really have is a normal-sized bathtub with a whirlpool.