It's not that big of a deal for a good pro. Best to rip up the floor to run it under the subfloor, if possible. Only problem may be that other piping or ducting is in the way, but you don't need much room for a 3/4-inch pipe. You may also be able to use Pex for gas supply in your area, which would probably make the job a little easier. Is the wall you're moving it to and exterior or interior wall? If you can't run it under the floor it may be better to bring the pipe in from outside if possible, rather than run it around the perimeter of your room (which I don't think the building department would allow anyway, unless you cover it with framing and drywall), though your co-op may not allow that. Another possibility is to run it from another pipe altogether, such as the one running to your furnace or water heater, assuming those are gas-fired. Check with your co-op board for recommendations for plumbers who have worked in the building. A good plumber will be able to tell you the best way to go.

Just want to chime in here for anybody else contemplating this in their remodel. We bought a Florida 1971 split-plan house on slab concrete and gutted the middle part, moving the kitchen about 10' over and added an island prep sink & gas range, and all the associated electrical needed for a 16.5' island (it's really a galley style kitchen but one side is an island). We were also pleasantly surprised how inexpensive it was to have the entire raised dining room removed and repoured along with all the trenches, especially thinking how many weeks it would have taken to DIY and haul away all the debris. (Just don't forget to have the dirt sprayed for termites before the pour! And keep the receipt. Don't ask how I know this.) When they jacked out the old plumbing, the drainpipe had completely rusted through under the slab, near the spot where the old sink was. If you could only smell the rancid grease that emanated from that section of pipe, you would never, ever, not even think about pouring grease/oil/fat/drippings/etc down a sink again - no matter how much hot water you waste after it. (If you ever watch "Dirty Jobs", you've possibly seen the one where he cleans out a rancid grease vat and was puking his guts out.) A relatively small amount of hardened grease allowed some water to pool behind it and rust out the pipe. Who knows how long the sink water had been actually draining out under the slab? Just keep in mind that this could happen to you!

I don't know if this is an option, but I'm in a townhouse where I can't alter the exterior so let me share what I did in a similar circumstance. We had a bank of three windows and wanted a wall where the middle window stood. I replaced the opening window with a solid window, and then protected it with a piece of marine grade ply painted white (to the exterior it looks like a white shade) and then drywalled over the window. On the outside we have three windows, on the inside, two. If we ever have to change it, it's some messy drywall work, no biggie really in the grand nature of things construction wise. Could you do something similar, then go with a non-flamable backsplash full height over the drywall (so the window won't get hot) and put your hood above? (live wire would be more likely to know if this will actually work than I am). As I mentioned, I was just building a wall, not worrying about heat. I think if it's possible, it's going to be easier to bump out that counter in your kitchen to a deeper counter (giving a space behind the stove) than to try to make an island work. Oh and one the code thing with island clearances...Live Wire may be quoting code in his area (he does know his stuff) but in my area, that is not a code issue (36" clearance around an island). They have a recommended size, but no requirement to follow that. (I'm smaller on the backside of my island, but there is a large door opening taking up most of that space so I didn't worry about it).

"I just think any receptacle in a kitchen, laundry room, or bathroom should NEVER be placed in the floor. " It may not be the brightest idea, but it is not prohibited. If it WAS a significant risk GFCI protection would be required. Note that placing receptacles face up in a counter surface IS prohibited. It would take a pretty decent leak in most cases to get water under a stove, over the faceplate, and even then the yoke of the receptacle is solidly grounded. "The GD and DW receptacles are off the floor. Not much chance of water getting to those." I cannot recall how many DW & GD receptacles I have seen face up on the floor of the cabinet under the sink. I always place them on a wall of the cabinet, but even this is not enough of a hazard to warrant either GFCI protection or a prohibition. Water and 120 V is not usually very dangerous unless the skin has been saturated. Thus all the rules for power around bathtubs, showers, sinks, pools, kitchen counters, & exterior receptacles. If you want to see a hole in the code, only 120 V receptacles for a kitchen counter require GFCI protection. The 240 V plug for an imported appliance placed above the counter does NOT require GFCI protection.