My friends and i just returned from 10 days in CR. We spent 4 days on playa tamarindo. like you guys, we are proud NEW YORKERS!
You will love the surfing on playa tamarindo, which is connected to play longoste and playa grande. There are 2 major places to rent gear and boards in the area. One that we used is Iguana surf in the middle of town. The waves are perfect for intermediate to experienced surfers. The vibe and people that tamarindo attracts is universal and young. We met people from all over the world and locals all under early 30's. The majority of tourists are americans, many seeking the same that you are. There are lots of places to hang, drink and party. We found the locals and non-americans to be a little bit more shy than new yorkers...we had to get the party started new york style!!! The monkey bar, El Pescador, and mambo club are very lively, you can go club/bar hopping to find the right vibe with just a short walk. By the way, there are no side walks and there is only 1 main road. so, wear flip flops and bring your heels to change into. The road is also very dusty and dry, your feet will need to be hosted down before you get into bed. Its all good though:)
A word from the wise about hotels, its fine anywhere you stay, it is pretty inexpensive in terms of accomadations and even food. The daytrips are pretty reasonable too. You can pretty much walk anywhere in tamarindo (like you would in nyc). JUST MAKE SURE YOU REQUEST FOR A ROOM AWAY FROM THE ROAD. we stayed 1 night on the road side and it kept us up all night. Then we were moved to an upper floor on the opposite side facing the ocean and it was soooo quiet and awesome!
Our friends stayed off the beach but loved their hotel and its cheap, and a 2 minute walk to the beach. here's the link:
We stayed here and loved it. Its more expensive then the hotel above, but we loved it. Its owned by a french family and there's a french bistro and great bakery for breakfast right in the building. The website doesn't do this place justice. Room #8 has the most amazing view. Here's the link: www.lalagunadelcocodrilo.com/english.html
Last thing, Tamarindo is suppose to be touristy, but we didn't feel that at all--even during high season when we were there. The hotels are all small and quaint, with 1 or 2 large resorts. They are all nested within trees so that when you look at the beach all you really see is beach and trees.
The sand is not pretty, but it is fine and powdery. Its more of a mix of gold, brown and grey. As for the water, its not turquoise like the caribbean, but neither are the others in CR from what I hear.
Our friends were only planning to stay for 3 nights but ended up staying for 6 for just the surfing. If that's what you are looking to do, you'll love Tamarindo!
Enough for now, write back if you need more help. Happy planning!