Mission trips are a lot of fun, but they are also a great blessing and time of spiritual growth. I've done several short term mission trips myself which you can read about here. It's a blessing being able to help missionaries, work, and evangelize. It's an awesome way to really do something for Christ. While my parents and the others were in Brazil, four people got saved during the church services! Praise the Lord!
Some people like to take vacations. They go on cruises, go to tropical islands, and take tours. Now, there's nothing wrong with vacations, and sometimes a rest is greatly needed. However, vacations are temporal. They are fun for a moment, but soon the memories fade. They accomplish very little (if anything) of eternal value. God's Word says we are to lay up treasure in heaven (Matthew 6:20). I wonder how many of us Christians would be willing to sacrifice our vacations for Christ? For the same amount of money (most likely even less), you could go on a short term mission trip. That memory may also fade, but the rewards in heaven will never fade away. The blessing of meeting and fellowshipping with other Christians is something that gives true joy. Knowing that you are making a difference for Christ by giving your time, money, and work brings a such a sense of fulfillment and JOY!
For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek.