We took a bus from Coco to San Jose for the first leg of the Coast-to-Coast trip. The bus stops every few hours at little markets where you can get ice cream, friend chicken, and gas-station fare. When we first arrived off of the bus we decided to take an Uber to the Airbnb, because they do use those in the capital city, San Jose, and the nearby airport city, Alejelah. There aren't really Ubers in other parts of Costa Rica, as far as I know. This was actually really important and we always use Uber in the capital city. Some might say its better to support the local taxistas and I understand that sentiment, however, the way the taxistas approach and treat you as a tourist makes it clear they really want to get as much money as possible out of you. The one time I took an independent taxista in San Jose I got charged about $200 and was given false information and the experience was quite unsettling. More on that in the post about Puerto Veijo Round 2.
Our Airbnb was an extra bedroom in a young man's nice apartment. He was a coder in the day and an artist and we had many great talks with him about the local economy and the future. He also was very kind and offered us snacks and coffee. We walked to the nearby market to get dinner and food for the next day. We actually both taught classes with Gogokid that morning in the Airbnb. which looking back seems like a lot of commitment. The following day we got on the next bus to Puerto Veijo.
At the time of writing this we've taken buses inter-provincial in CR dozens of times and the bus system in pretty awesome. Now we have a dog, so things might be more complicated, but in general the buses are really well equipped and reasonably priced. Going from either coast to the capital is less than $15 per person, and there is always under-cabin storage - plus, we had BIG bags the first time around.
It would be a bit of a challenge to go across the whole country in one day by bus, but it certainly could be done. The best course of action is to get from where you are to San Jose, and then stay a night at a hostel or Airbnb, visiting the bus station to find out what time to be there for the next day to go from San Jose to your final destination. Another big tip is to not travel during Semana Santa (Easter week). Probably about 80% of Ticos travel to see their family or to vacation spots around the country and the public transit is a nightmare. Taxistas are also extra aggressive during this time.
In general to find out the bus times, you can search online and hope there's a recent blog. Even better, you can find a sign at the stop or ask the bus drivers, and they generally know the times for their station and may have some knowledge on the connections you'd want to take. You can ask around other people in town as well, as a lot of Ticos travel for family or business. This is another example of when knowing a little bit beyond basic Spanish is helpful.
Also, some areas of CR, such as the peninsula with Santa Teresa and Nosara, are only accessible by ferry.
On to Puerto Veijo!