I want to have a good text book lying around that keeps my skills sharp...machine element design, strenght and materiels, life time anaysis...or all of the above.
A good text book to keep which skills sharp? Have you been working in machine elements? Or structures? Or...Or...Or? To "keep" skills sharp, you must already possess them, so there should be a particular area that you are "keeping sharp".
If you are just looking for problems to work in a variety of areas, I like "Standard Handbook of Engineering Calculations" from MacGraw Hill Publishing.
"Spoken" like a true gear-head! I will say that I've been amazed over the years at how much information is in Shigley, assuming you are referring to the "Handbook of Machine Design" (also published by MacGraw-Hill, I believe). LTOP lists himself or herself as "mechanical", so you're probably on the right track with Shigley...I was going broader.