If you have a DD or hiring a driving company Mirmar would make for a great beer day (Alesmith, Amplified, Pure Project, Green Flash, + lots more). If looking for drunken stumbling then top picks would be North Park followed by Ocean Beach.
Hiking wise, i honestly don't enjoy San Diego hiking overall. All dessert and rocks. Suggestions would be Stonewall and then hitting Alpine pub, or walking Sunset Cliffs and hitting up OB after ( least spot for sunsets, plus sneaking a can or two isn't hard. Also there is more seclusive hiking/paths at the most southern part of Sunset Cliffs Blvd). Another good coastal hile is Torrey Pines. There are trails that lead to the ocean for a fun day at the beach (secluded so a beer or two discreetly is fine), finding a good place to park just usually sucks.
The reason i mention drinking discreetly is drinking in parks and beaches is prohibited and you can face large fines. At remote places you should be good, but don't try at Ocean Beach, Mission Beach, La Jolla, or Missing Beach.