A trip together can reveal many things. It is like taking a short-term course to know each other faster. If you have been in a relationship for some time now and want to take it a step ahead like you are considering asking your partner to move in with you, then it is better to take a trip together before that. It will give you a complete insight into the person that you are with.
A few weeks or a month-long trip will unravel the person's true nature. In a mundane life, a majority of your time is spent in your office. Although you will spend enough free time with your partner, there would be many other distractions in your life like a social gathering, spending time with your own group of friends separately once in a while, and whatever little time you find to be with each other you will both try your best to be presentable. You are not yet showing your real self to the other person, as you are still in your shell and taking time to come out of it.
When you go on a trip, you will have all the time for yourself and a great chance to discover each other. One another's habits, what s/he likes or dislikes, decision-making skills, organizing skills, personal hygiene, and many other things will fall out of the closet. These little things about each other are going to be a big part of your life if you are planning your life together ahead.
With all the time together, you have enough time to discuss your past, your present, and your future with the other person. You will have enough opportunities to discuss several topics like music, movies, emotions, travelling, environment, cooking, literature, art, politics, etc. These discussions will help you know what the person is most interested in and also lets you know what your common favourite topics are that gets you both bond better. When you open up to each other, it will help you both feel comfortable in your own skins and that is when things will start settling for both of you. The common opinion and difference in opinion all matter a lot in the long run. You can also get a chance to discuss your future together, if s/he sees you in his future, marriage, kids, etc.
The new place, the new situation, how the other person handles the finances and reacts to any kind of stressor such a language barrier, food issues, jet lag, and how you respond to each other in a stressful situation will all give you an idea of each other's threshold.
If you have opted for a lodge with a kitchen and have decided to save money on food while travelling by cooking your own meals, it will give you a good idea how good you both are at cooking and sharing the chores. Unfortunate situations like falling sick while travelling, will make you realize how much the other person cares for you and is willing to take care of you.
In an unknown place, your partner is the only one you know and it will help you develop complete trust on that person. You will feel like you are a team and have each other's back when in any kind of undesired situation looking out for each other and supporting each other.
There would be many things that you start liking about the other person as well as some habits that can really aggravate you. You will able to gauge and judge if the good qualities outweigh the bad ones or you can find a common ground where you can ignore the bad qualities for the good qualities and decide to have a future together or if you cannot put up with the person and want to part ways after reaching home.
Whatever your decision may be, but travelling with your significant other will help you have a memorable trip and also gets you decide about your future if you have been unsure about it so far.