Bay seniors, puzzled by, but eager to understand why coffee has become such a local obsession may want to sign up for a Coffee Roasting and Tasting Tour. You’ll find a serious one in Emeryville on select Sundays from 10 to noon and 2 to 4. At Highwire Coffee Tasters you will learn to taste the difference between Yirgacheffe, Las Crucitas and Camiseta and dozens of other cherished, esoteric beans. Usually $200, the tour currently has a special on Amazon for $90. Reservations required.