Least expensive? That would probably be #3, as you can go right over the tile. Before installing a floating laminate I'd recommend you walk on a few. They can take a bit getting used to, and the sensation is dofferent depending on the manufacturer. Fine Homebuilding Magazine (taunton.com) addresses laminates in this month's issue. For laying new tile, in Florida, unskilled labor for demo is quite reasonable ($). If it's a large area of floor, then it might be worth it to hire that out, that way when the installers come in to put down the new tile any problems with the substrate will be theirs to address, in that they cannot blame damage to the existin slab on you because you did the demo. You also won't have to deal with hauling and disposing of the old tile, either. If you;re on a slab and after tile removal your installer discvoers problems with the existing slab, then you might have to have a membrane put down, that could add a couple of dollars per sqft to the new tile cost. So...I think a laminate over the existing tile would, overall, be least expensive. But if going with new tile and you insist on ripping up the old, I recommend you write a check for the whole shebang. Mongo

It's true ... mosquitos love dark places during the day and crawl spaces are a favorite. The deck being only 2-3 steps high is close enough to the ground to warrant a patio. You could raise it a little with a retaining curb. At 18" or less above grade, I'd opt for patio. At 18" to 24", it's a toss up. Above 36", I'd opt for deck.

I would be careful about the three-pane patio door you are considering. If the panes are too narrow (meaning if you are intending to decrease the size of the individual panes that you currently have, in favor of adding a third pane) the divide can end up looking like prison bars that block a lot of the incoming liight and obstruct your view due to added trim around the individual panes. Also, consider how you will dress the wider door for light control and privacy--patio doors are often a challenge. Your current patio door doesn't line up at the top with the window above the sink, and the window in the adjacent living room? Maybe a taller patio door would work better than wider patio doors? If you have two-lite windows in the adjoining room I would keep it consistant, both in color and number of lites..

Rather than needing to replace the deck or porch each decade or so, consider first creating a small corner porch by the door with a concrete floor, with the vertical sides faced with either brick or stone. You could then add steps of the same brick or stone -- perhaps with a right angle wrapping around two sides of the porch -- and use the same stone or brick to outline a concrete patio.