I know Class 4 pretty well and these are my predictions from the St. Louis area teams:
District 2: Ladue
St. Mary's could give Ladue a scare in the semifinals and if they don't come to play against probably MICDS, then they'll be in trouble, but the Rams are solid all around.
District 3: Parkway North
Probably the most intruging district in Class 4. You got the Vikings, Parkway Central, Zumwalt East, and St. Dominic. We'll have too really good semifinal matchups. I think North is the best team because of their defense, home field advantage, and enough on offense to get it done.
District 4: Parkway West
Really thought this would be Westminster's year to get out, but at 2-6 it's not looking good. West has a good defense as well as a complicated offense to crack if they get rolling.