There are different perspectives on "glad" and the word is not necessarily "less formal". See this passage from the Bible that has inspired an anthem, "I Was Glad", and a hymn, "Jerusalem", both of which were sung at the wedding of Prince William and Kate Middleton.
1 I was glad when they said unto me, Let us go into the house of the Lord.
2 Our feet shall stand within thy gates, O Jerusalem.
3 Jerusalem is builded as a city that is compact together:
4 Whither the tribes go up, the tribes of the Lord, unto the testimony of Israel, to give thanks unto the name of the Lord.
5 For there are set thrones of judgment, the thrones of the house of David.
6 Pray for the peace of Jerusalem: they shall prosper that love thee.
7 Peace be within thy walls, and prosperity within thy palaces.
8 For my brethren and companions' sakes, I will now say, Peace be within thee.
9 Because of the house of the Lord our God I will seek thy good.
King James Version (KJV)