We just put down my dog (and former partner) a few months ago. Our next will be a Great Dane. They don't fit the bill for small, but they are low-key and family-friendly. Out dog breed book actually recommends them for apartment-dwellers because they are so laid back.
If you want to go small, I had a Westy growing up, and he was a great companion. I don't like small dogs, and my wife hates them (she worked for a vet for years, and the small ones were the meanest), but some other smallER, laid back ones that havn't been mentioned are:
Bassett Hounds are good, but like all hounds, bay...
bulldogs can be hit or miss, but mostly laid back.