I'm known as being a brutally honest person. I admire your car, so keep in mind I have no "hate"..LOL..with that in mind:
The style of the rim looks nice. Personally, I think 19's are one size too much for the LS, as it was never engineered for that size wheel. But to each his own.
That wheelwell gap is horrific and totally unacceptable for anything less than a 4X4 look.
But its a double edged sword. If you lower it (which you must do), you run a STRONG chance of some sort of rubbing back, front, or both. Rolling the rear fender lip *might* help, but based on that offset I think I see, I doubt it. Plus the 19's will only add to rub potential.
30 Series tires WILL result in a harsher ride. It's totally normal to mentally wish it to not feel harsher, but it is harsher, due to less sidewall rubber for impact absorbtion. It will become harsher if you lower it, due to less suspension travel. The harshness doesnt always show up at first, but over time, it will present itself.
With all that said, the wheels themselves look nice. And I like the color of your LS.
Good luck