On the topic of the younger son hating his father. It is not said that he hates his father, and I don't believe that he does... but in asking for his inheritance... it is like wishing his father were dead. That had to hurt the father. Yet the father took him back unconditionally.
As for the older son, that has also been on my heart a lot. You see my sister ran away from home. When she returned I was glad and celebrated, but at the same time it was frustrating. Where was my reward for being the good daughter?? The father's response to the older's sons complaints is, "Everything I have is yours". God gives us everything! He gave us His Son and eternal life. At the same time, the father's plea to the older son to join in the celebration, is how God us to celebrate when others grow in relationship with him.