I think anything handmade is a worthy gift and I would guess that a 60-something year old couple would greatly appreciate it over something impersonal. However, I'm in the camp of making sure I have an idea of the recipient's style, color and/or taste by asking friends/family. I think it raises the odds that everyone is happier in the end and more important than a "surprise".
As for ideas, I seem to always settle on a cozy lap quilt because it's not permanent and you can never have too many! I just finished a few for (distant) relatives in Oregon and backed them with minky because of their climate.
Look forward to more ideas and seeing what you decide on! I'm sure your handmade gift will be well received whatever it is!