When it gets to be summer, many nights of the week you can find my at one of the free concerts that takes place around town. My all time free venue is Grand Performances in Downtown LA:

http://www.grandperformances.org/

I also love the two Levitt venues, Pasadena and MacArthur Park:

http:///www.levittpavilionpasadena.org/

http://www.levittla.org/

The Santa Monica pier has free concerts on Thursdays:

http://santamonicapier.org/twilightconcerts/

Also on Thursdays is the Skirball series:

http://www.skirball.org/programs/music

Again, all of these concert series are FREE! At some of the events you have to pay for parking. 
And it is always a good idea to get to the venues early to make sure that you have a place to sit or stand.

I do want to highlight a few events which may have particular appeal to us PUGsters. Coming up on Saturday the 22nd at the Levitt MacArthur Park is the retro Twenties group Vaud and the Villians.

On Wednesday June 26th in Temple City the Phat Cat Swingers play a free outdoor concert. and then Sunday July 21st they play in a park in South Pasadena:

http://phatcatswinger.com/shows.html

I hope that this info may be useful. Summer is a time for fun, free fun so have at it. BTW most of these venues do not allow alcohol. Grand Performances is the only one that actually allows it. But if you know how to be discreet...