We express our appreciation by saying "Thank you". The question is do we say it often enough? There are many occasions when it is appropriate to say thank you in private. It means even more when we say it in public.
Take thank you speeches to teachers for instance. Most teachers do their best for the students in their care. Many of them give extra time and effort to outside school activities such as drama or sport. Often they spend time helping weaker students. Isn't it appropriate then that somebody says "Thank you for all their hard work?"
Wedding speeches are not thank you speeches per se but they often contain an element of thanks. For instance the bride or groom may thank their parents for all the love and care they have given them over the years. They may thank them too for the help they gave in preparing for the big day. Such words of thanks are deeply appreciated by parents who usually put a lot of effort and perhaps money into the preparations for the wedding day.
An anniversary speech is often another occasion when thanks may be expressed to parents for their caring over the years. Of course when it is a special occasion such as a silver wedding anniversary or a golden wedding anniversary it is almost obligatory to express your thanks in a loving way.
Eulogies are not described as thank you speeches but certainly they are in a way giving thanks for the life of someone special. Whether the speaker is speaking about the companionship of a good friend or the love of a sibling by giving a eulogy they are saying thanks for years of caring and sharing.
In companies there are many occasions where words of gratitude are appropriate. Thank you speeches are given when somebody has spent many years working for the firm. The C.E.O. or manager will often express his or her thanks to staff at the Christmas party or the Happy Holiday function. He or she may also express his or her thanks for work well done at a staff outing. When a new company or branch is being opened words of thanks are often expressed to those who have helped a dream become a reality. Put simply such speeches are good for morale.
So while we may not describe them as thank you speeches there are lots of times when we should take the opportunity to say "Thank you."