Griffith Observatory, Los Angeles
The 'Griffiths Observatory', shut for renovation while I was there, but a great place for views of the city and the Hollywood sign. Set at the top a hill in large park area to the east of LA.
The Griffith Observatory is a fun place with many good shows and interesting things to learn. Very cool Laser show set to music. Of course, you could head into the desert to California City and go for a sunset skydive.....