The Sphinx occupies a prominent space on the same plateau as the Pyramids of Giza, just downhill a little and due east from Khafre’s (Chephren’s) pyramid (the middle one) but still inside the compound’s walls and gates. Visiting the Sphinx is included in the price of the same ticket that gets you into the Pyramids complex, but you may need to show your ticket again to a legit local door guy to enter the Sphinx Temple complex down below its base. Some people never wander down there, but if you do just know that the much less aggressive guy at the door there asking to see your ticket is on the up and up, unlike those after the gates and security at the main entrance.
The Sphinx is pretty amazing to look at and take in and take photos in front of, but some find its smaller size a little underwhelming in comparison to the big daddy monuments that serve as its backdrop. It’s still pretty awesome, although it has certainly taken quite a beating over the years from erosion and other abuses (e.g., the missing nose).
When taking the inevitable set of photos in front of the Sphinx, make sure to get some fun ones posed to look like you’re smooching with the Sphinx, leaning on the Sphinx, holding up the Sphinx, etc. If you’re alone, or if you or your traveling companions aren’t good at creative photography, there are usually many school-age children around who will offer to prop you up in all kinds of poses and take the photos for you for a little compensation. I generally like taking these kids up on their offer for this because they tend to be good at it since they do it every day and because they’re adorable kids who don’t really hassle or pressure tourists like their older counterparts do elsewhere around the plateau.