Brookfield vs. Elm Grove   Year Founded: 1954 Population: 39,740 Scouting report: Brookfield has become a powerhouse suburb, mixing residential and commercial growth with a ferocity few can match. Brookfield Square and the shops on Bluemound Road are as attractive to outsiders as the beautiful homes and strong schools. Access to major freeways and thoroughfares also make it easy to get in, out and through Brookfield, whether it's heading to the mall or just heading home.   Year Founded: 1955 (Although railroad officials called it "Elm Grove" as early as 1856) Population: 5,941 Scouting report: Named for its trees and marked by its traditional feel, Elm Grove is unique for being traditional, eschewing cookie-cutter developments for historic homes and wooded lots. Elm Grove has been recognized nationally for its trees and birds, thanks to a focus on maintaining the integrity of the village's wooded history. Few street lights, sidewalks and light vehicle traffic make Elm Grove one of the calmest and most serene suburbs you'll find.