Our summer holiday we did in Guam. We stayed for 5 days there. It is a really great holiday island. The beaches, the weather and sea is perfect.
You have some interesting shopping places, especially if you search for American products and sizes that I do not get in Korea. One day we rented a car and went around the island. If you are interested in culture and history, Guam is not the first choice.
If you want to have beaches, sun and sea, it is a perfect place.
I did the first time snorkeling. I am sure it will not be the last time.