I've been on a couple of Discover Outdoors trips, and their guides are personable, outgoing, and well-trained. On the Hike & Hound trip, a small group of New Yorkers and their dogs were led on a a moderate hike to Pine Meadow Lake. We returned to the city with one tired doggy and lungs full of fresh air.
They also offer hikes with adoptable dogs, hikes and wine/beer/whiskey tasting, and multi-day trips. This is a great way to meet new people and a hassle-free way to get out of the city and enjoy some of the beautiful hiking opportunities in the area.