You can almost never build it too big. Have enough room for the sunning chairs plus room to walk in front of them comfortably....probably close to eight feet front to back.....more is better. Your own ability to judge what's practical and fits into your poll, yard. landscaping, etc. but if there's doubt, make it bigger.
Bigger is always better when it comes to decks, but as a minimum you need about 8-9' width to accomodate lounge chairs with a little room to get by them. Two lounge chairs will take up about 5' width if they are put right next to each other and if you just want a small bistro seating area that could probably be done in about a 5' area as well. So that is a minimum of 9'x10' not counting additional room for a landing, if needed at the top of a set of steps. Without a little more information I would say that 10' width and about 14' length would be a good size for what I think you are describing.
If you have the lounge chairs and a seating area, lay the furniture out in your yard or driveway and see what feels comfortable to you and use real measurements.
I'm still trying to figure out where to put the pool and where to build the deck. I know you can't pick a place for me because it is personal preference, but I would still like some ideas or suggestions.
Does anyone have any recommendations about how close or how far an AGP should be to my house? I don't know if this is possible but, thinking about hurricanes knocking pool walls down and flooding my house.
When you walk out to your backyard, would you like to look at a pool with nice landscaping around it or a deck?
I personally do not love the looks of AG pools. My back yard also faces the main road in and out of our subdivision, and I want it to look really nice. When we get ours, it will butt up to our existing deck, and be decked all around, with lattice at the bottom of the deck, so that it looks like a giant deck, and not an AG pool. Of course, I am in KY and live on a hill. In NO, you don't really have that option unless you build the deck off your second story!!
SO, in a flat-terrain situation, I think I would prefer to see landscaping, not a deck sitting in the middle of the yard. Put the deck off to one side, and landscape all around.