Weber's Genesis series is pretty much top rated by Consumer Reports. I have a Genesis Silver A, a smallish grill, but it works REAL well for parties of up to 20 or 30 people. I can't grill that many burgers at once, but then, I can't really do a quality grilling job on that many burgers at once.
Heat is excellent. It generates 500-600 degrees of heat under the cover without much problem at all. I pre-heat until the thermometer pegs then throw the meat on to sear. Turn down the heat after searing both sides and grill.
The bigger models (Silver B and Silver C) are much larger and have side burners for lobster, vegetables, etc. These grills fall within your price range.
Ducane is over-rated.
Jenn Air now offers a high end grill that looks exceptional.
One thing to look for in top end grills are solid grilling grates. The average cheapy uses chromed wire, the Webers use stamped, heavy gauge steel covered with porcelain, the best grills use massive cast iron grates that look like the Weber grates, but are solid and very heavy. They hold the heat very well helping to keep the temperature more constant when you open the lid.
Nice thing about the Webers is the dripping catch trays underneath. The cheap grills have sold bottoms with a drain hole for letting out excess water, the Weber has a large opening with a dripping funnel and a catch tray beneath that. The drippings drain off rather than building up in the bottom of the grill speeding corrosion.
Whatever sort of grill you buy, clean it well every fall before putting it away for the season. Getting rid of all the crud build up will dramatically increase the service life of your grill. Also, using grill paint to cover areas of corrosion (after cleaning and degreasing them, will also keep the grill working longer.