I will express my great thank to Eric and his family. The apartment is located in a very safe and clean neighborhood, 5 minutes' walk to Starbucks and 15 minutes' walk to Clayton metro station. If you take lyft or uber, it will cost you ~$5 to WashU, ~8$ to Delmar loop (the commercial area close WashU, where you can find very good restaurants and grocery) , and ~$9 to Forest Park. People walk or jog in the street, so if you prefer exercising on foot, do it as you like:)
Eric and and his wife are super nice. We checked in at ~10pm the first day, and he waited until we arrived. They are friendly and are willing to provide help for our travelling (travelling tips, restaurant suggestions, etc). Their daughter Elfie - who was 9 months old when we were there - is very cute and sweet. They invited my partner to read English rhymes for Elfie. We all enjoyed a lot during our stay with them. They even prepared a card for my partner to thank him for his reading.
If you are lucky, you will meet their neighbor, also a friendly lady with a girl dog. We met them one day as we came back when she was opening the door to receive a mail. We greeted and the dog was more than excited to meet new friends!!! They brought extensive happiness to our trip.
I will highly recommend if you are visiting St Louis or WashU. A friendly reminder is: Just be a little gentle after their baby is asleep.