There are several reasons why you would want to visit Monteverde. We actually went there for main 2 reasons: 

We heard a lot of people talking of how amazing the experience of "flying"/ "hanging" over the rain forest is so we said we should take the chance of being in Costa Rica and book the Tour offered by 100% Adventure.

The Canopy  tour was 45$ per person and included:

• the equipment (you can get a helmet on which you can mount a go pro
• supervision stuff
• 5 canopy lines (if I am not mistaken)
• one rappel 
• 2 supermen (including the 1590m long one)
• one Tarzan Jump 
• possibility to buy pictures 

After a intense start of the day and hiking Cerro Chato (HERE details) we left to Monteverde. 
There is a TAXI - BOAT - TAXI  trip that brings you to Monteverde. As far as we checked online, ideally you should book one day in advance. One of the companies that are available is Anywhere Costa Rica . We did not book them in the end as we found a cheaper alternative through our hostel 
(Cabinas Las Palmas). 

our plan for the day was to make it to Monteverde, so we decided to wake up early and go for the Hike, exciting as we were on tight schedule. The bus to Monteverde was leaving at 2PM. 

We woke up at 7AM and we arranged with the hostel owner (cabinas las palmas) to drive us to the entrance of the trail and then at 1 PM to pick us up and drive us back to the hostel. the idea was to have time to shower after the hike and he was nice enough to have our room cleaned the last one.  

- the drive to and from Arenal Observatory Lodge was 4000 colones for 3 and we decided to take as we were as said in a hurry 
- entrance fee for the hike 10$ for students (without a guide) 
- La fortuna waterfall entrance was 11$ for anyone 

Follow the way back to San Jose (HERE the details from the road to Tortuguero).
- Boat Tortuguero - La Pavona (11:00)
- Bus La Pavona - Cariari - take a seat and wait they don't have real arrival hours, it depends on when it comes from Cariari based on the departure hours 
- Cariari - San Jose - there are several buses (as before you need to walk to the new bus station)