Thai women for the most part are extremely different than Western girls because they are taught from early on that it is their job to take care of their husbands. For this reason they find it normal and even joyous to cook and take care of almost all of the household chores. Due to this fact, Thai girls leave no question in your mind that they sincerely care and make a point in showing it every day by all of the small tasks that they take care of in the home.
On the flip side, one thing you will notice that is different and perhaps not always acceptable depending on how you feel about in-laws, is that families are very close-knit in Thailand, so it is expected that you will be around the Thai girl's family on a very regular basis.
In particular her parents are extremely important and you will be expected to help her care for them as they grow old since Thai Buddhism teaches children since birth that they need to honour their parents by taking care of them in old age. This means that you will be expected to either invite them to move into your home or pay for their needs if they do not have a great deal of money.
Thai women also are in love with the idea of romance and "true love", and will expect to find romantic surprises woven into their time with you. For those that are not very romantic or have no idea of what your girlfriend or wife may want, there are plenty of websites that offer some insight into how to meet Thai girls' expectations of romance and some great gift ideas.