My gas grill is a Weber Summit S-670 with a natural gas hookup. As GlennK said, they are not cheap, but this will last. I wanted this grill for some time, but was waiting for my last Weber Genesis to kick the bucket before buying the Summit. After 13 years, the Genesis refused to die and I eventually gave it to one of my brothers.
I use all of my grills year round almost exclusively instead of the indoor oven - easily at 90-10 ratio for grill to oven at our house. I only clean the cooking grate after preheating for a new cook. I keep the stainless steel clean as I go, but not excessively, and I do a thorough cleaning every spring.
As for the burners and innards, the burner tubes are under warranty for 10 years, the stainless steel grates and flavorizer bars for 5 years, and the stainless steel shroud itself for 25 years. I'll be shocked if I have to replace the grates or bars after 5 years as they still look brand new after almost two years.