Floor for a screened porch?

Building from the ground up (replacing a deck), but yes, pier and beams.

If you do tile, you will probably have to lay down a plywood subfloor, then hardi-backer over that. Then the tile.

It will probably get pretty expensive. Also, tile outside in the humidity will get pretty slick.

If you go the deck route, normal practice would be to roll screen over the floor joists and then put the decking down on top. This keeps the bugs out from the bottom.

Flagstone would be better than tile.

Tile or flag stone will pop up outside unless installed on concrete. Besides that, you talking a shite load of weight for a decking. Best to just use treat T&G lumber. Let that dry out a couple months and come back and stain/seal it. That will get the look you are looking for.

I bought some wood look title at Lowes 5-6 years ago. It was 6x48" I believe. It was the best looking version I had ever seen and looked like real wood once it was laid.

However, I wouldn't personally put tile on a deck. It will be very slick and you'll have cracked grout joints in no time.