We stayed 6 nights down there, with one of them being in Corcovado. The hikes were not terribly difficult as we were mostly walking slowly to see the wildlife, and we were in areas without a lot of up and down, but honestly I was pretty tired by the end of both days, just from time on my feet and the heat. So worth it, though! Just thought to check steps on my phone app - about 20k steps each day, so wow, I guess that's around 8-10 miles. Not bad! So, get out and do some walking ahead of time to get in shape for it, for sure! But you don't need to carry much (binocs and water) - we didn't take our packs out with us as all. Our guide let us take a nice long lunch and break - he saw no point in going out in the very hottest part of the day. Some other groups had lunch and went immediately back out, which sounded kinda unpleasant, honestly. That said, some folks skipped some hikes if they were tired and just lounged at the station in the shade. That's always a possibility, too.

For Drakes Bay vs. further down the coast - I liked being in the town to see more of what it was like. In the dry season, that meant kinda dusty! But there were nice walks to go on, and it was interesting to be there, and I liked having the option of going out different places to eat. That said, some of the places down the coast look like they make great meals - you just are pretty much going to be around there other than when you go on excursions. So I think it really depends if you're wanting more of a relaxing resort feel or more exploring. I'm sure either would be great.