Lafayette Square

One of St. Louis' most affluent and oldest neighborhoods, Lafayette Square has what you're looking for. From large, stately mansions to small townhouses to churches made into condos to nice mixed use apartments, The neighborhood has a plethora of different types of homes. At the center of it all is Lafayette Park, a pleasant tree filled park were dog walkers, joggers, and others all coexist. The neighborhood is also extremely kid friendly, and many parents with children were walking through the neighborhood. The neighborhood is not very bike or transit friendly, being far enough from a MetroLink station (Union Station) to walk, but too close to take MetroBus (#80, #11, #4, #32, #40X), and having no bike lanes along Truman Parkway (the Road between MetroLink and Lafayette Square). Other than that and the fact that its not a very affordable place to live, a great neighborhood. 

Tower Grove South

Though census records suggest St. Louis is in decline, Tower Grove South gives a different view of the city. Bounded by Tower Grove Park, Kingshighway, Chippewa, and Grand, the neighborhood is extremely diverse. Old homes run all along the side streets, and the bustling South Grand and Morganford business districts have low rise, mixed use apartments lining their sidewalks. Homes range from 80k-200k, and rents are just as diverse, making the area very mixed income. Many ethnic restaurants were also in the area. The housing style and alleys made the residential streets look a lot like Chicago. Having St. Louis' most frequent bus line, the #70 Grand, is also very helpful in making Tower Grove South into an amazing urban neighborhood.