There are two museums at the Chino airport, Planes of Fame and Yanks. Yanks has improved greatly in the past few years and has a great display of 30's and 40's light aircraft in addition to a modern section.
For hobby shops, Tony Naccarato now is holding down the fort at Smith Brothers Hobby in Reseda. There is also Covina Hobbies in West Covina on Citrus, about a mile north of the 10 freeway. Finally, Pegasus Hobbies in, either Clearmont or Monclair (they are next to each other, and I can't remember which one it is)
Flying sites are Whittier Narrows (most active on Friday, these days) and the Sepulveda Basin. Whittier is at the intersection of the 60 freeway and Rosemead Blvd. in El Monte. The Park is in four sections. The flying site is in the Southwest corner of the Northwest section. It is visible on Google Maps. The Sepulveda site is between Burbank Blvd. and Victory Blvd. west of Woodley. There are both RC and CL sites at both places. In addition, on Sundays, people fly lightweight FF gliders and rubber power at the Balboa lake site known as the "Grassy Knoll" (actually, just north of the lake itself).
If you want to see some slope soaring, Point Fermin is spectacular and very popular. It is in San Pedro at the intersection of Gaffey St. and Paseo Del Mar.