Since it's a built-in function of Bridge, this slide show is always available and it's easy to useand you don't have to have the photos open to run the show.
In Bridge, select the photos you want to show by Command-clicking (PC: Control-clicking) on them (if you want every image included, you can skip to the next step without selecting anything).
Press Command-L (PC: Control-L) to open the slide show, then the Spacebar to start it. You can also press H to access various slide show controls. Press Escape to end the show and return to Bridge.
You can use the Bridge slide show to rank your image by pressing 15, or open an image by pressing O.