Whenever I'm finding a good breed for someone, I usually go by eliminating Groups.

In your case, you want a laidback dog who generally does not require a lod of exercise. Immediately, I'd cross off the Sporting Group. Sporting dogs, as a whole, were created with strength and energy to run all day and not tire out. Today, these dogs are usually not used for field work, but they still maintain that sense of drive. So, now we have Hound, Terrier, Toy, Non-Sporting, Working, and Herding. Honestly, I'd cross off Herding Group as well. Most herding dogs have a high energy and intelligence level. Case in point, Aussie Cattle Dogs. Though these dogs are very small (18" at the withers), they're very driven and intelligent. The average home is not suitable for these guys. I'd also cross off the Terrier Group. Incredibly vivacious and bold, Terriers are prey-driven dogs with a fair amount of energy. An active home is best for Terriers, Sporting dogs, and Herding dogs.

So, we are left with the Toy, Non-Sporting, Working, and Hound.

Out of these AKC groups, I'd recommend most of the Toy group, many of the larger Working dogs, and a retired racing Greyhound.

Out of the Toy group, I admit I'm biased towards the Pekingese. These dogs have a very low exercise requirement, but are full of character. They're bold and do require a firm loving hand, but once you earn your way as Alpha, they'll stay loyal and obedient until the end. Amazingly stubborn and aloof, these dogs are VERY wary of strangers. However, they never sound the alarm unless there is an extremely good reason (doorbell ringing). However, if you cannot devote an hour each week to grooming a Pekingese, you can clip the coat down. The only thing that I would warn you against is their high maintenance. You need to pluck the dog's ears twice a month, and clean it diligently with storebought ear cleaner/powder. As well, you should wipe down the facial wrinkles to avoid skin irritation.

As for a retired racing Greyhound, these guys are generally laidback, though many a young 2-4 year olds have proven this statement wrong. In the house, most ex-racing Greys are couch potatoes. As we speak/type, my girl is sleeping soundly in her bed. I'd say the only time she isn't sleeping is when we walk her for 20-30 minutes each day and when she's eating. But if you let her loose in a dog park/dog trail, she lets it all come out. She'll run like there was no tomorrow. So, in the house= calm dog. Out of the house= powerhorse (most of the time). Good Luck!