16x32..enough for a large table, sizeable seating area and gas grill
Built it myself 18 years ago. Pressure treated underneath with mahogany decking and cedar rails. This year I will do my first repairs: Replacing single 1x4 mahogany deck board, one cedar rail and 2 cedar balusters. Other than that it's been staining the deck every other year and painting the rails white every 5 years (with some very minor touch ups on the top rail in beteween). Love the size, love the look, happy with the maintenance as it is what I expected. Chose hardwood as I really dislike the trex stuff as it stains, looks fake, flexes too much (Def needs to be 12" oc) and warps.
Hardwood decking is a SOB to work with as I needed to pre-drill every hole and use ss ring nails ( that would bend if not driven perfectly straight), but was absolutely worth it to me in the end. I still get complements on it today as it looks good as new. Meanwhile my brother built his of PT pine at the same time and has rightly hated his ever since he built it. It looks like crap, splinters like crazy, doesn't take stain well.
My advice, spend a bit more and use a Brazilian hardwood. Plan to do some annual maintenance. Enjoy having the best deck in the neighborhood.
Good luck.