I love the views in Grecia and the cooler temps, yet I was not a fan of the steep, winding roads. Yet the higher you go, the cooler it gests. This is pretty much the case all over the Central Valley. Highs can be in the 80s and nights can drop to the 60s-70s, depending on where you are.
I stayed here in Grecia (https://www.tierranuevacostarica.com/) and absolutey LOVED the esperience. The food at the restaurant was so delicious and the owner personable and able to share a lot of info. There is also a weekly expat meet up on Wednesdays at 12 pm at Los Jardines Vivero y Café (https://www.facebook.com/losjardinesgreciacr/?locale=es_LA) -- I would just call to confirm with the restaruant in case the day/time changes.
I stayed here in Atenas (https://hotelcolinasdelsol.com/). It was fine yet a plus was its central location. There is a woman's group in Atenas who has a weekly meet up (https://www.facebook.com/groups/663758784658197?locale=es_LA) and I think the husbands also have a men's meet up.
I consider Atenas and Grecia more expat hubs. I never stayed in Heredia, yet I seem to always drive through it.
I find Facebook groups very helpful when I need to learn more about an area. You also might want to ask questions in these groups:
https://www.facebook.com/groups/128010388878472
https://www.facebook.com/groups/425764764900687
https://www.facebook.com/groups/620448778305789
https://www.facebook.com/groups/517401048358283
I suggest joining us at the CR conference in May this year. It is held in Escazu and contains a wealth of information. And then you could explore the other areas a few days before or after. I find that visiting and meeting people is the best option. Almost everyone I meet who has relocated tells me that they just knew when they visited a certain area that is would be home. Good luck and how exciting! Costa Rica is paradise for many. Come see what you think about it for yourself!