I haven't seen you in ages (donkey's years). That is, donkey's ears is rhyming slang, replacing years with ears, while donkey's years reverts to years, with donkey acting as emphasis. “Donkey's ears” implies “a long time” because donkey's ears are long, while “donkey's years” is supported by the belief that donkeys live a long time.
La-La Land: a euphoric dreamlike mental state detached from the harsher realities of life. It refers to the mental state of someone who is not aware of what is really happening. La-La Land —used as a nickname for Los Angeles, California.