Beagles have very sweet dispositions and are rather bumps on logs.... and don't get all that big.
Greyhounds are also very sweet tempered dogs (especially if you can get a rescue dog or a retired racer) they like to run really fast for short bursts, but then sleep the rest of the day.
Bulldogs ugly as sin, but loyal, patient and very sweet low mainteance dogs. my brother has one.. somedays betty pretends she's stuffed and doesnt move.. but will go for walks when asked... is social... Wil put up with abuse by children and well the downside is they snore like fred flinstone... [/QUOTE]
The only breed I agree with here is the beagle. While Greyhounds are calm, they are not small. Also BullDogs can be very wild and have numerous health problems. I hate working with them when they come into my clinic. I am trying hard to think of a small calm dog and the closest thing I can come up with is maybe a Shi-tzu or a Sheltie.
The thing about finding a calm dog is that EVERY dog is different. It's hard to say really that one breed is more calm then the other. I would recommend going to the shelter and picking one based on the behavior you witness. After all mix breed dogs are known to have fewer health problems.