Either way is legal as far as the electric is concerned. Note that you need two receptacles since the island is over 9' long. They do not have to be on different circuits but they do need GFCI protection (the protection can be provided by an upstream GFCI). Note that if these are below the countertop surface, they must be within 12" of the top and under no more than a six inch overhang.

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If this is a post tensioned slab, you don’t do any of that without an X ray and engineer standing by on full alert.

Run both electrical and plumbing underfloor (you know water only flows downhill, right?). The vent for the sink will be done as an "island sink vent" (==>Google image it) according to your local codes, so make sure the cabinets have the room to account for those bends or an AAV as required.

At some point someone will probably want to remove the columns.

Thanks guys! Ron, the GFIs are marked on the plan :-) 3onthtree- yes, that's what i'm leaning towards :-)

Drain lines only go downhill. Supply lines have no problem going up under pressure (though you lose about a half a psi per foot of elevation change).