Hi!
I am currently a 4th year in STL and I grew up here, so maybe I can help some. There are 5 total IM Residencies in STL: Washington Unviersity, Saint Louis University, St. Luke's, St. John's and St. Mary's. I would list them as follows in order of reputation:
-> Wash U: University program, excellent clinical training, competitive, residents train at Barnes and the VA, takes about 40 residents/year.
-> SLU: University program, great clinical training, not nearly as competitive as Wash U, residents train at Saint Louis University Hospital and the VA (Wash U and SLU split the VA services/patients), takes about 25 residents/year.
-> St. Luke's: Community hospital/university affiliated, from what I hear is a pretty cush program, work with a lot of private attendings, residents train at St. Luke's, hospital/facilities are great, takes about 13 residents/year.
-> St. Mary's: Community hospital/university affiliated, residents train at St. Mary's (primarily known for it's OBGYN care), takes about 8 residents/year.
-> St. John's: Community hospital/university affiliated, hospital itself is great with excellent facilities (residents get $18/day for food - cafeteria is excellent), residents train at St. John's, takes about 7 residents/year.
As far as living in STL, the city/county is extremely patchy. There are some bad neighborhoods and literally if you go a few blocks in one direction you can go from nice neighborhoods to the ghetto. Be very careful about where exactly you decide to move. It is not exactly the most exciting city ever, but it does have some fun activities for families (zoo is great and free, science center, forest park, grant's farm, butterfly house).
I hope this helps, if you have any more specific questions feel free to PM me. Good Luck!