The work is important to the quality of life of individuals. Seniors face the difficulty of staying in the labor market. Is important the preparing for retirement phase and participation in all spheres of social life.
Preparing for retirement and "work" occupations in retirement are both important, but seperate issues. There is some research out there on the retirement process, but if you're looking to follow someone's research, Jackie Boehm from James Cook University is starting some research in this area. If you're looking in to productive occupations in retirement, volunteering appears quite important. The benefits of volunteering can be looked at from multiple perspectives. There's a Foresight report on mental health that looks at general population needs and suggests volunteering as part of a five-a-day. In terms of seniors, my own paper in to time use of community-dwelling older people suggests that volunteering is one of the only time use factors associated with life satisfaction.
The research program of Dr Jo Earl at the University of New South Wales may be of interested to you. Here is website on which you will find some of her publications and resources: http://www2.psy.unsw.edu.au/Users/JEarl/.
One of my research students is currently finalising her thesis on retirees' experience of returning to work. We hope to publish the report in 2014.