expression, noun
rich kid; person who grew up wealthy
Often used with a slightly critical or envious tone to describe someone from a privileged background who may be naive or sheltered.
彼はいいとこのお坊ちゃんで、苦労を知らない。
He's a rich kid who doesn't know hardship.
いいとこのお坊ちゃん育ちだから、世間知らずなところがある。
Because he grew up as a rich kid, he can be a bit naive about the world.
お坊ちゃん alone means 'son of a wealthy family' or 'young master'; いいとこの emphasizes the 'good family' background.
お嬢様 is the female equivalent, referring to a young lady from a wealthy or high-status family.
From いい (good) + とこ (contraction of ところ, place/family) + の (possessive particle) + お坊ちゃん (young master from a good family). The phrase literally means 'young master of a good family'.