Thanksgiving is a great holiday, because like FloCarson said, you can reflect and give God thanks for everything you DO have. It's a time to be thankful from the little things in everyday life, to the major things in life.
But I think one of the great holidays out there is Easter. It signifies the glorioius ressurection of Jesus Christ, the Lord and Savior of this world. He came down to earth, was born of a virgin, lived a perfect, sinless life and then went and died on the cross, sheding his sinless blood for our sins. Three days later he victoriously ROSE FROM THE DEAD, proving all he said and taught was true and that he was the true Son of God. All who come to him in forgivness and believing he is who he said he was, (Lord and Savior, the Son of God) have their sins washed away, and they have guarenteed eternal life with God, and do not have to pay for their own sins. That my friend is truly AWESOME and something to be very, very thankful for.
-Jimmy-