Outside of Jack London Square at night is a little dicey, but there is nothing to do once you are a couple blocks from the Square anyway. Inside Jack London Square is plenty safe at night if you use good common sense. There is the Waterfront Hotel
at JLS which is pretty nice. There is also the Marriott Courtyard in downtown Oakland. There are other hotels in the area, but those are the only two I would consider staying in. During the day walking from the Courtyard to JLS is about a 20 minute walk and would be safe. At night I would take a cab for your own safety
If you like jazz there is Yoshi's across the street from JLS. There is also the Fat Lady where sometimes you can hear an opera singer which is a block away from JLS, and a relatively safe walk at night. At night the only other attractions at JLS are Scott's restaurant, Kinkaid's restaurant, Heinhold's First and Last Chance Saloon
(not to miss), where Jack London hung out and a few retail shops that are still open at night. If you are into canoeing or kayaking there is a rental place there, during the day of course. You can also catch a ferry
to San Francisco
from JLS, which might be nice if you want to see SF at night from the water
. The SF Bay
is really pretty at night.