We live in Tucson and thicker coated dogs seem to do well here as long as they can get out of the midday summer heat. My mother in law next door has a chow and a golden, they both do very well. The chow gets shaved in the summer, but the golden just keeps her coat year round and she has never had any problems. They are both in their teens now.
Shorter coated dogs would work too. The only concern I would have is sunburn, especially if they ended up picking a lighter colored dog. My aunt has a bull terrier with white markings and they have to put sunscreen on his white spots or he gets terrible sunburns in a matter of minutes. I imagine a greyhound with white or light spots could have the same problem.
As far as breeds go, goldens and bernese mountain dogs sound like good fits. As do greyhounds. I'm a grey fan, and the other bonus to those is that you are getting an adult dog that has had their drive and temperment assessed already, hopefully making for a good fit with the family.
Smooth collies are very mellow and laid back, friendly. Nothing remotely like border collies. A close friend has one from working lines that she has trained for search and rescue. Even though he is a drivey working dog, he is EXTREMELY mellow, lives with 4 cats and a boatload of chickens. He doesn't pick up and get active until they put his working vest on. HE reminds me a lot of a greyhound though. He'd be content to lay in his bed all day, every day, if they let him. Very easy to walk too. They never had to teach him not to pull the leash. I don't know what state you are in, but there is a collie rescue in Phoenix that gets smooth collies in pretty frequently.
I don't know if I would get a standard poodle. Every standard poodle I ever met was VERY standoffish to anyone except their families. They definitely seem to be a one-person dog. If your parents are worried about the dog being good with guests or other people they meet on walks that might not be a good choice. Other than that, they seem great for the people who live with them.