Picnic tables are always a nice addition to your yard. Picnic tables give the feeling of lots of family fun. I know when I see a picnic table I think of birthday parties, BBQ's, games to play and more. Adding a picnic table to your yard will give potential buyers the same feelings. The more you do for your home to give those who are looking to buy a warm, comfortable feeling the better off you will be. Potential buyers want a home that they can imagine themselves being happy in for many years to come, so take the time to do what ever you are able to do, to help them achieve this feeling.
If your yard is large enough you may also want to look into adding a gazebo. These are beautiful and are quite useful.