Last time I was in the great state of Washington I bought a 3 piece set made by OTC that has a knurled extension built in to each socket. It came with the two standard automotive sizes (5/8" & 13/16") along with a special 9/16" socket for Ford's 5.4L 3V engine. I payed about $30 over the counter at an industrial supply store, probably much cheaper online. They are great, since then I have hardly used any of my other plug sockets. Very well made, exact fit, tight fitting boots, nice finish, the built in extension is very, very helpful. No country-of-origen though, so I assume they are Taiwanese.
Plug sockets can be purchased with a u-joint built in to the socket. Craftsman sells these.
For the ever present problem of the socket sticking to the plug after installation a 3/8" extension with a locking tip works great, much better than trying to fish the socket out with needle nose pliers.