Sue K.

I have a Genesis and like it a lot. Indirect is easily accomplished using only the back and front burner.

Currently I have the stainless steel grates, but have had cast, and porcelain on previous grills. I suspect the stainless is the most substantial, but they will all deteriorate over time. Keep the grates of any grill coated and seasoned with cooking oil and they will last a long time.

I actually have one weber grill, and one viking. I don't find too big of a difference between side to side and front to back, besides where you put the meat if you don't have all of them on.

I prefer stainless steel. Making sure they're clean and seasoned is important, and I've had mine for over 4 years.
I could imagine that the iron would get rusty if the enamel comes off.