Companionship
Senior dogs whose lives have been disrupted in their later years have so much love to give and like nothing better than giving it. They tend to rely heavily on their owner for companionship and therefore bond very quickly. The desire to reciprocate the companionship given to them is very strong.

Ease of Care
Senior dogs, in most cases, do not have the same exercise requirements as their younger counterparts. They have experienced the chewing/destructive stage long ago, and want nothing more than a warm pair of feet to lie by or a soft lap or couch to snuggle on. Their daily/weekly walks can be therapeutic for both dog and owner! Although some senior dogs may require more frequent veterinary visits, the joys of owning a senior dog will greatly outweigh the effort involved, as will the extra years of companionship gained.

Who says you can't teach an old dog new tricks?
You sure can. While it may take an older dog a bit longer to adjust to new situations, they can; they will; they do. Their only requirement is to be given the opportunity. Generally, older dogs are calmer and therefore will focus much easier on what you are trying to teach them.