Also, it's important that if you leave it up, stay under it. You need to get the rain water out of it before it collapses any members, and it will.
Leave the cover on, just make sure it's dry when you put it away. If it's not and you have to leave, take the cover off.
As for brands, the best I've seen are the King Canopy Tuff Tents. A little more $$, and weight, but you get stronger frame members that can withstand the high winds and water collecting. The upper frame extends into the middle of the tent, which can be a head knocker if it's lower, but makes the entire unit considerably stronger. You also get pull rings instead of buttons for the takedowns. After a year or two those spring buttons get more difficult to push. They also come with walls usually. You can really tell the difference.
All of that said, I have a cheaper one that has no internal bracing. I think it's an EZ-up in fact. I've had it for 4 years now, and as long as you don't leave it up in a storm, it has provided me with invaluable shade on 99F days here working on shows. When I have to buy a new one, I'll probably go to Sam's Club and buy the heartiest King I can put my hands on.
