I just read all the Kingdom Come comics: Kingdom come, The Kingdom, They Kingdom come, and the few supporting comics.
I read the original story when I was younger and always wondered what happened after the ending of Kingdom Come. Well since I have DCU now… 
The whole series was phenomenal! I really enjoyed the whole dilemma with Kingdom Come Superman (Earth-22). I also really enjoyed the story involving Power Girl in the JSA series.
The original graphic novel (Kingdom Come) was so good and I didn’t think the follow-up installments would be any good, but they were great! Highly recommended for any DC fan!