If I was staging Romeo and Juliet and had to show the Montagues and Capulets similar class status and wealth, but also make them recognizably different I would use different colors with the characters costumes. I would have the Montagues wear darker colors and have the Capulets wear much lighter colors. I would do this to show the difference between the two. Think about sports teams, the two teams wouldn't wear the same color because you wouldn't be able to tell the difference, you can tell the difference of them because they have two different color jerseys. Only Romeo and Juliet would wear similar colors to show their bond and connection. The two families would be treated like royalty. They would have drivers, servants, assistant, and etc. That would make the audience see that the characters are important because usually upper class people have all those things. To show the people that the Montagues are enemies I would add some competitiveness. One always trying to beat the other in a activity. I would also just throw some history into it. Maybe the families had bad history with their ancestors involving some stolen money or something like one grandfather killing the others.