Since I've started using ultrasonic diffusers years ago - I simply can't travel without them. A diffuser is one multi-tasking heavy lifter that I can't leave at home. I'll give you the superficial first. My hotel room or airbnb simply must have a clean, fresh vibe. My diffuser and oil blends do just that and set the tone for my trip.
Now you might be thinking, well, why not just use a candle? First, many candles have difficulty scenting an entire space and if they can usually (not always) they are filled with synthetic chemicals as scent boosters which are generally toxic. Even naturally derived candles can be problematic. Here's a great summary on this here and more information here and here. And of course diffusers don't involve fire and smoke which is important especially for spaces where that’s a no-no. The worst that can happen is when you throw off an item of clothing with wild abandon, you knock it over and it spills yummy scented water.
But the benefits don't stop there. Certain essential oil blends can actually reduce and kill pathogens in the air, literally helping to get rid of a) the previous occupant's germs or b) the smell of cleaning products. Other oil blends help with relaxation because sleeping in new places can be hard sometimes and other times a luxurious wind-down after a long day of sight-seeing is exactly what is needed. Also they can help you breathe better and reduce the opportunity for allergens and congestion. That's a huge plus!
And finally, if you are sharing your space with someone else, e.g. a partner and your space is small, put your diffuser right outside your bathroom. Trust me on this.
Travel by itself is generally great, but this is an easy and inexpensive way to help make it transformative.