Puerto Viejo and Manuel Antonio · Costa Rica · North America
A week is a choice between coasts, not a tour of both. Pick by default and you pick wrong.

Tested by Paulius Pikelis · 140 countries
Costa Rica makes you choose. The Pacific and the Caribbean sit a few hours apart with a spine of volcanoes and cloud forest in between, and in a single week you realistically do one of them properly, not both. Pick by default and you will probably pick wrong.
The Pacific is the side the brochures sell. Surf towns like Jacó, the wildlife crowds of Manuel Antonio, resorts, paved access, English on every menu. It is easy and it is busy. The beaches are fine but rarely quiet, and the polish comes at a price: a lot of what you do here is packaged, ticketed, and built for a steady stream of visitors. If you want low-friction sun, monkeys, and a surf lesson, this side delivers without making you work for it.
The Caribbean side felt like a different country. Puerto Viejo and Cahuita run slower, the culture is Afro-Caribbean, the jungle comes right down to the water, and the whole coast carries a looser, less manicured feel. Fewer resorts, more rhythm. The trade-off is that it is wetter, scrappier, and you give up some of the postcard beaches for somewhere that feels lived-in rather than staged.
My honest read: if this is your first trip and you want the easy version, take the Pacific and accept the crowds. If you have travelled a bit and the word catered puts you off, the Caribbean rewards you more for less money. Trying to cram both into seven days means a lot of driving and not enough of either.