In a word...Weber. I spent years buying charbroil and other less expensive brands every 2-3 years. Last fall, I broke down, listened to a buddy, and bout the three burner Weber Spirit E-310. It's right at that $500 mark you mentioned, but it's already proven it's worth what you pay. Grates are heavry cast iron. Yeah, they take some work to maintain, but not so much to be a problem. It's hot. Real hot. Six hundred + degrees in about 10 minutes with all three burners on high. Steaks get great grill marks and a good sear at that temp. chicken skin actually crisps up from the heat. Warrany? Yep, a ten year warranty on most of the parts, and customer service is outstanding. My buddy often calls for his issues and has new parts sent to him, free, within a day or two.
Another piece of advice after you buy the Spirit...save up another $100 and buy a Weber One-Touch Silver charcoal grill at Target or another store. Having both a gas and charcoal grill may seem a little much, but in my backyard, I use gas for anything that will cook in under an hour, and break out the charcoal for the occassional weekend when I'm grilling something that's going to be low and slow...ribs, beer can chickens, etc.
And, be sure and buy a cover for the grills. Protect your investments.
