A Utopia is a place where nothing is bad. Everyone smiles. Everyone laughs. Everyone is happy. Of course, children still cry when they fall and scrape their knee. The death of a loved one is still a sad occasion. But hunger is not felt. Disease and death are not feared. All hate is fleeting and love is abundant. There is a strong sense of "help your neighbor and your neighbor will help you." That's how these people live.
Everyone lives in the exact same house regardless of job. There are no promotions in jobs. Once you reach the age of 18, you are placed in whatever career you choose. It is surprisingly balanced. Most children tend to follow in their parent's footsteps. Most parents have the same career. Once the career is chosen, the young adult is tested and placed in the position most fitting to their skills. There, they are happy. It works out well for them.
Responsibility for the children is shared throughout the community. The child goes to one home every night, but throughout the day they go wherever and are watched by whomever is available. There is no marriage. A person may have children with whomever they wish or choose not to have children at all. They may live with anyone, but they may not claim possession. Everything is shared. Jealousy is rarely felt.
There is no religion. It was decided long ago that it is easier to doubt something than nothing. Everyone is told from the beginning of their lives that there is nothing after death. The idea upsets some people at first, but they soon learn not to care. When asked about how the earth came to be, they are told, "I don't know" and are forced to live with that response. As they grow older, they accept it. The only science that is done is involving medicine.
The one problem with this society is that there is still disease. It can make a life very hard, but the community is always there to help the sick person live until the end. Life is valued immensely because they can expect nothingness after death. Best be happy now and save the tears for the eternal darkness that awaits.
The laws are simple. Do no hurt others. Do not covet others. Do not hate beyond the recommended healthy time period, a day and 2 hours. Do not do anything to upset anyone. And so on. Those who break the laws are cast out. There is technically a vote, but it is always unanimous. After generations of living in this way, the people are happy and unwilling to change. The desire to stay is what keeps them happy. And they like it that way.