Free Summer Concerts @ Point Loma Park

http://www.plconcerts.org/

Coronado

Ride your bikes along the harbor then catch the ferry to Coronado for $2.50/each way.
http://www.sdhe.com/san-diego-bay-ferry.html

If you go on a Sunday you can enjoy live music from Frank Sinatra imitators as the sing near Peohe's. Pack a sack lunch and you're set or ride your bike across the street to Tartine and get a sandwich or pastry to go - yum! http://www.tartinecoronado.com/

and/or ride them to any of the amazing parks & beaches on the island. My two favorites are the Sprekels Park (off Orange & recently re-done - great place to throw a birthday bash) and Tidelands park (bayside). http://www.coronadochamber.com/visitor/parks.asp