Russell makes a nice billit sandwich type. As you said, easy to install, and fewer lines and fittings.
A lot of people don't reall understand how the thermostat works. When cold/closed, it allows about 10% of the
oil to flow through the cooler. This allows all the
oil in the system to warm up at the same rate. You wouldn't want a valve to open and get a sudden slug of cold thick
oil.
The Dow side of that is at cold temperatures, your oil will never warm up. Even when covered with something, it can be tough to get the oil up to operating temps.
You really only need a cooler when racing, or on really hot days at slow speeds. The rest of the time there's no need at all.
If you install your lines useing a sandwich adapter (no thermostat), you can use a manual valve. Make an H with the lines and place a manual cut off valve on one side, you can turn it off completly.