Lake Merritt in Oakland is beautiful. It has enough running/walking/strolling paths all around for a few miles (I forget how many but like 3 I think). Lights are lit up all around at dusk till dawn.

Also, you can rent a gondola and have a wonderfully romantic afternoon with a picnic basket or chocolates.

Geese are protected and are rather bossy as geese usually get but even more so because they are so revered and everyone has to bow before them.