OK, Viazul only has a few departures per day and you can't squeeze into an Astro bus at the last minute, but wait, there is something better.
I went to Cuba for 10 days over X-mas with my girlfriend and we managed to find someone to drive us around in their private car. It was the best thing we've ever done there. The price per day was cheaper than renting a car and it definitely beat being crammed in a bus for hours on end. We went all over the island, and having a local show us around was great. We definitely discovered the cheapest eats and didn't have to worry about accommodation - we stayed with their contacts around the country.

Since we loved the experience so much, we decided to give them a hand, and created a website for them. you can visit it at http://www.cubavroomvroom.pcriot.com. You can also email them at cubavroomvroom"at"gmail.com cubavroomvroom"at"gmail.com to arrange transportation. They have some access to internet, so give it a day or so to get a reply.

Journey to Cuba