Santa Barbara, California
The beautiful Pacific Coast and, duh, wine
If you simply must do the whole California wine thing, do it in the "American Riviera" of Santa Barbara. The 200+ wineries here have not only proven themselves more nimble and experimental than those in Napa: they contend with drastically different growing conditions, thereby producing drastically different wines. The region also beats Napa in the looks department; ringed by the Santa Ynez Mountains along the Pacific Coast, Santa Barbara is pretty as a picture, and you will take lots of them. Stay in Los Alamos, which retains its Old West charm despite its newfound trendiness for farm-to-table dining and family-owned estate wineries (the Presqu'ile Winery is a highlight).
If you’d rather skip the drive into the countryside, head downtown to the The Funk Zone -- I swear to God it's called that -- a warehouse-turned-arts district with 10 walkable blocks of excellent restaurants, galleries, and shops. Take the gang to a brewery, distillery, beer bar/bottle shop, and multiple wine tasting rooms that compose part of the Santa Barbara Urban Wine Trail. Stay at the boutique Hotel Indigo, or go full college dorm throw-back at the Wayfarer, provided your friends would enjoy shared hostel-style rooms, and “on-site amenities” like inflatable oversized red pool chairs, giant Jenga, and cornhole.
While you’re here you can also kayak through sea caves, hike to waterfalls, bike down the coastline, surf, get open-air rooftop terrace massages at Bacara Resort & Spa, or play bocce on one of Pure Order Brewing Company's two Olympic-sized bocce courts. The drawback: it's California, so it's expensive. Beware the May Gray and June Gloom (California’s foggy season). Early spring and fall are lovely, with the added advantage of being a bit cheaper and less crowded.