The folks at Costa Rica Discount+ were excellent in working with us so I promised to write a review on TripAdvisor. However, since I don't see an open thread, I will just write my comments here. My friend and I were staying in La Fortuna/Arenal and wanted to drive to Manuel Antonio. We did a lot of research on our own to identify the most reliable car rental companies in those areas, and Alamo was definitely our first choice. I read about the discount card on one of the travel forums and purchased both the car rental discount (20% off) and activities discount card for our trip. Didn't end up using the activities one, but the car rental one was well worth it. Immediately after purchase, I received an email from a representative offering help on planning our trip. I figured asking for help wouldn't hurt, and told her our situation. Over the next two days, we got several quotes on major companies and she answered our questions about road conditions as well. Fast email response and efficient. She put us in touch with a guy at Alamo across from the hostel we were staying at, and we finalized the details the morning of the rental and set out for Manuel Antonio. It was a thoroughly enjoyable ride with no complications with the rental company, and we would rent again with Alamo through Costa Rica Discount+ if the occasion came up. It cost us $130 for the car, GPS, and minimal insurance for one day. Note: Most Ticos drive manual, so automatics are relatively scarce. If we could drive manual, it would have been cheaper. A 4x4 is also not needed for the roads from Arenal to La Fortuna.
As for the activities, we weren't too sure about what the discount card suggested because they weren't raved about on TripAdvisor, and time was pretty tight to get them to negotiate with the companies that we wanted to take our tours with (we were literally planning day by day), but I am sure the staff would have been just as helpful with planning activities as they were with helping us rent the car. I'd advise you to plan ahead if you want discounts on your activities too.