It depends on how big your house is. Our deck is 660 square feet: roughly 15' x 50'. It's all relative. :-)

I think we are leaning towards a smaller deck that leads down to a paver patio area. Ideally we would have just done a paver patio but due to daylight windows we need stairs to go down the back of the house. Due to this, we thought we would do a small sitting area deck with 2nd level paver...

There is no standard size but I would keep it in even lengths , if you are thinking about PVC or PVC encapsulated or strait composite I would stay with 12', 16', or 20'. That's the length they are made and to cut off a foot or two just because your deck is a different size can get pricy. Most of the new products cost between a low of 2 dollars a foot to almost 4 dollars a foot. Those pcs in the scrap pile will add up to some big bucks