I lived in Los Angeles for many years
& there was no Dominican parade. There is a Puerto Rican festival for "el dia de San Juan" around July every year. You will meet many Dominicans there!
In LA dominicans get along well with there similiars (Venezuelan, Cuban, Panamenos etc.)
There is a Park in Gardena (Alondra Park) where they play softball on Sundays. You can buy Dominican food & meet many people there.
I'm not sure if it still goes on but try and look it up. Club Social y Cultural Dominicano, Lawndale, CA. Sorry don't have their number anymore but I will ask around for you. They also have yearly mothers day parties & 27 de Febrero etc.
By the way just a couple of weeks ago I was flying back from Santaigo and met a girl on her way to LA. Dominican from Samana on her way back home to the San Fernando Valley. Her dad is Mexican & her mom Dominican.
Good luck