Santa Monica. Third Street Promenade. They usually get larger inventory than the Manhattan Beach Apple Store (these are the two Apple Stores closest to LAX)...
I tried for three days to get the iPad 2 64GB 3G ATT in Black at the Manhattan Village store and was unsuccessful. They had others, though...I hit it on the fourth day at the Santa Monica store...which seemed to have huge stocks of everything but the lowest cost model, the 16GB Wifi only.
This was about a month after launch last year.
I'm sure the Apple Store at the Grove will have good inventory..but the crowds will be huge...and the Grove's parking situation and constant traffic is enough to send most sane people over the edge.