I have a Golden (Ben) & a Lab (Sajdeh). The vast majority of young Goldens & Labs are sweet and hyper!! Many Goldens and Labs go over an 'energy hump' around 4-5 years of age. If you were willing to contact a rescue and tell them who you are looking for -- 5+ years old, calm, couch-potato -- they might be able to help you make a good match.
I got both of my dogs when they were about 8-months-old (I had Ben about 2 years before I got Sajdeh). Even though they were 8-months-old when I got each, and required virtually no potty-training, I did not think I was going to survive the 2-6 month adjustment period. Ben ripped up installed carpet, pulled down curtains, ate plants, and counter-surfed. Sajdeh ate socks, chewed books, jumped on the coffee table for fun, and - when he first arrived - attacked Ben when I made the mistake of not locking him in a crate until after Ben finished eating.
Should you get a dog? Are you gone for a max of 10 hours a day (and can make sure your dog gets out to potty sometime during that period)? Are you up early in the morning before work and/or late in the evening - so that you have time to enjoy each other? Are you willing to let the dog sleep in bed with you?
I was lucky that the animal rescue folks kept me from getting two dogs at once. If you think you want two dogs, get the first, get it settled into your home and bonded to you, then get the second dog. If you get two dogs at one time they bond to each other and they won't see you as the pack leader.
If you have room in your heart for an elderly dog - it might be great for you both. Too many elderly dogs are abandoned when they become slow, or not-so-cute anymore, or when they develop a chronic health problem that requires attention (even if the attention is minor).
Dogs who really need a savior know when they have found one and are forever grateful. I can't take in anymore pets right now, but if, in future, I am ready to get another dog - I would love to find an elderly dog...
Almost Heaven Golden Retriever Rescue
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http://www.almostheaven-golden-retriever-rescue.org/doglist.html>