Hi, the taxis will always make a quick stop in Havana first, before going to the bay of pigs. But the ride is quick(faster than the viazul bus) and only costs about 40cuc per person.
Here are the instructions:
From Vinales to the bay of pigs you can use a communal taxi. In Vinales, in front of the main square, there is a tourist information office with posters and prices marked all over the windows. In front there is almost always a taxi organizer who can help you arrange a taxi to Trinidad. The cost is about 40cuc per person. The organizers name is Leonardo. His phone number is 5 240 9142. He speaks a bit if English. But either tell your landlord to call him and organize the taxi, or go visit him in front of the tourist office. He has short, black hair and he will probably approach you if you look like a tourist. There is always a crowd of people in front of the office and many drivers offering rides all over cuba. But i know this organizer and he is professional and has always given good rates. He can arrange the taxi to pick you up at your casa and take you, along with a car full of other people, to the bay of pigs or Trinidad, or playa larga or cienfegos, by way of Havana. It will be a 1950s station wagon or small truck.
I warn you, bay of pigs is a rather dull place. Do your research. Playa Larga is good. Trinidad is popular. But the bay of pigs, despite being popular, does not have much to offer. The town is small, dusty and rather boring. The beach is rocky. If you go, dont stay long. You might be more interested in Trinidad and playa Larga. Take care. Mario