If you are going to Hermosa avoid the north end, that's where all of the tourists hang out. It's, what, 3 miles? of beach, but everyone always clumps up right by the backyard bar. I will never understand this.
Food and drinks. get some ceveche from the guys on the side of the road. AMAZING. Beers are surprisingly the same price in the grocery store as they are at the bar, so no excuse to stay in!