V.M.
the drawback with completely enclosed parks is that they often do not have restrooms. - there is a small park on the corner of Prospect and 21st in Hermosa Beach, it is completely enclosed, but has not restrooms. few blocks off to Redondo Beach there is a bigger park on Pullman - also nicely enclosed, no restrooms. depending on the time of the year, i'd also look into Round Table Pizza in HB - they used to have nice BD packages and Adventureplex in MB - bit more $$$, but lots of fun.
Good Luck
V