since retirement. The Elders and Sisters are great to deal with. Many of the other adult couples can be a nightmare for your enjoyment. Older couples can be very cranky and it is their way or the highway. They seem to forget that this is volunteer service and not a job that one is getting paid to do.
Make sure that you select where you would like to go. You do have that privilege as a senior couple. As long as you are reasonable, you will probably get one of your choices.
Choose your assignment carefully. There are some great assignments and there are some lousy assignments. Make sure that you are selecting something that you will enjoy.
The mission president will make or break the mission for younger and Senior missionaries. Some MP's are dictators, others are kind, gentle and a joy to work with. Usually mission presidents serve in cycles. (1). Hard Core, follow all of the rules, dictator style. (2). The next president after that is kind, caring and a joy to work with. You definitely want choice #2. Hoopster is correct. Call, write or e-mail the mission president of where you have a desire to serve. Some are great in letting you know what they would like you to do and in asking what you would like to do. Many just want Senior couples and will work around duties in order to get some extra help.
Some missions are a great adventure while others can be boring. It is what you make of it.