I think I would need more info about the wet for sure. As I see the space I would run a deck from the right end of the house all across the back to that door on the left. I don’t know what that gray box it beside that door. I would do all one level level with what you have at the kitchen door . At least 12’ out from the house so that you will have space for a dining table , some seating and a BBQ area. IMO a railing would help define the area and also make it safer for use.You could easily combine a railing with steps down in 2 places, I also would think a deck around the above ground pool would be nice . The deck should be simple , as far as floating that is nor going to happen but there are concrete deck posts thta can be used to keep decking pretty dry and just use pressured treated decking or Trex for the boards and posts . As for the size measure what you need to put on the deck to make sure 12’ will be big enough. I love decks we have 2300 sq ft of deck all around our above ground pool and the house , it is like have another house outside and IMO so much more user friendly than grass.These are deck blocks and the one pic shows how they keep the wood off the ground

Thank you for that suggestion but the area gets really wet as the land slopes toward the house and the blocks may sink. We will put pilings instead and only want to go up to the chimney. So about 20' out from house and 30'long. Were trying to keep it lower so no railings were needed so it also remains more open flowing, easy on and off.

Also wanted to go further out on right side to "hide" air conditioning unit, possibly by putting the barbq there.