Which rules from The Giver would be useful to incorporate into a perfect society?

Rules regarding housing and feeding the population are useful.

It is actually very hard to cherry-pick rules from the community that we might like for our perfect world.  It is more of a package deal.  However, the best thing about the community is probably the fact that everyone has housing and food.  Although this is part of a larger collectivist effort, in theory it is a wonderful idea.

Everyone in the community is provided with a dwelling or some kind of housing.  Of course, everyone is given a job for life too.  There are no homeless.  At the very least, I think it would be nice if we could find a way to house people who do not have homes or have a job for everyone (although maybe not going so far as to force specific jobs on all people). 

The disadvantage to everyone having housing in Jonas's world is that all of the dwellings are alike.  

Furniture was standard throughout the community: practical, sturdy, the function of each piece clearly defined. A bed for sleeping. A table for eating. A desk for studying. (Ch. 10) 

There is no individuality.  This might be more of a function of all of the other rules of their society than the fact that the community provides housing, but the fact is that most of the dwellings look alike.  Of course, everything else is the same in Jonas's society too.

In addition to providing houses, the community provides everything else a person could need.  Food, medicine, and any other supplies are delivered each day and that’s that.  No one needs money, and no one has money.  Everything you need is provided, but what everyone gets is the same.  There is no more or no less.

Then he checked those outside Food Distribution; it was always fun to help with the deliveries, and he hoped he would find his friend there so that they could go together on the daily rounds, carrying the cartons of supplies into the dwellings of the community. (Ch. 4)

Of course, we do get hints that some people in the community are considered superior. The Giver has slightly better furniture. This kind of makes you wonder how the Elders live. There may be some favoritism going on in this society. It does seem to have a seedy secret underside.  Once Jonas experiences the memories, he learns that things are not as perfect as they seem.