When a Chinese say "你看看人家" , that means he/she is talking about someone with admiration or jealous, because he/she cannot do what the person did. Normally, it is positive. Basicly "瞧你" is negative. It means " Look at you, why you cannot do what others can?" There are also exceptions. If somebody did more than what you had expected for you, you can say " 瞧你”in a soft way。That means " oh, look at what you have done. You donot have done so much ,That made me feel I owe you too much" . Or when you are trying to comfort somebody who is crying or in sorrow, you can also say "瞧你" in a gentle way. That means " you should not have been like this" . In Chinese , 瞧=看，so you can see " 瞧你" or " 看你"， "你瞧瞧人家" or "你看看人家"

你看看人家主要侧重于夸奖别人。而瞧你则侧重于贬低你！

it is right, 瞧你=you look at yourself,你看看人家=you look at others but 都用于指责别人, it is wrong. they are both used for blaming the second person, but not the third. 你看看人家 is used for praising others in order to blame u, 你看看人家，多好，再看看你自己，多差。In general we never said：你看看人家，多差，再看看你自己，多好。we never praise someone like this. when u look down upon someone, u can use 瞧你，for instance：瞧你，什么鬼样子！it is very impolite, just like:What the hell are you doing!

你看看人家，通常接下来会说别人是多么优秀，有很多优点。 瞧你，则有点瞧不起的意思，是指说话对象不如别人。

瞧你=you look at yourself,你看看人家=you look at others ，都用于指责别人，are all used by censure someone.this is used to revile against someone，not politely，you would better not use.这是骂人的话，不礼貌，最好少用。