@Jim Kittridge Depending on your area, Absentee owners could be getting dozens of offers from other investors. Senior homeowners can be a good target because they are often ready to downsize or transition to assistance. An added bonus is that quite often they won't have done a lot of updating so they aren't expecting as much as their neighbors with the new kitchen.
Consider:
Senior homeowners with 15+ year ownership
Home value based on medium values for your area
single family home
No trust of company owned
A good motivational criteria to add in is Low Financial Stability Scores.
I think that it is more important to concentrate on the content of your mail piece rather than the form it takes - Make it BENEFIT driven. You can make easy for them to sell their house. They don't need to fix it up or have people walking through looking at their life. You can recommend movers, you can do the clean-out.
As you know, the list is the smallest cost of your campaign. You should consider working with a list broker to get a second list and alternate your mailings.