Third person plural
I am not new to Spanish by any means, but I have to admit the 3rd person pronouns keep giving me trouble.
My question is this: When speaking to a group of people (and I DON'T want to use vosotros) which pronoun do I use? I was taught le is proper when talking to a person formally, but when talking to more than one person formally, do I use les or los?
For example, if I wanted to say things like "I miss you (guys)" or "I want to see you (all)" would it be "Los extraño" or "Les extraño".... "Quiero verlos" or "Quiero verles"?
It continues to aggravate me. 
Please help me get this straight once and for all!!!
2 Answers
Well the basic grammar rule is that you use direct object pronouns (such as los) to replace direct objects and you use indirect object pronouns (such as les)to replace indirect objects.
If you're not sure how to tell if you're working with direct or indirect objects here's some examples:
Lo vi. I saw him.
Just you and him involved so 'he' is a direct object. He is seen so the verb acts directly on him, making him the direct object.
Same for 'I saw them' 'Los vi'.
But for 'I gave them an apple' there's you and them and an apple in between. The verb of giving acts directly on the apple, as it's the apple that is given, so 'they' whoever they were, the lucky recipients of the apple, become the indirect object 'les di una manazana.'
Sometimes the direct object is not so obvious but it's still there making the recipient an indirect object. Eg. Les dije que no. I told them 'no'.
There's you and them and the thing that was said. The object of the verb was what was said so 'they' must be the indirect object, indirectly receiving the action of the verb.
It's all quite logical, the trouble is that although these grammatical rules exist and are quite logical, if you listen to Spanish speakers from Spain those rules are commonly superceded by leísmo - as shown in your two examples.
According to RAE the masculine singular indirect object pronoun is the only accepted form of leismo but other forms are in use and are I face preferred in some parts of Spain. Eg. Lo vi. = Le vi. = I saw him.
Eg. I saw them = Los vi. (Used in Latin America and the only form accepted by the Academy) but Les vi. (Unaccepted by the Academy but preferred in parts of Spain).
So at the end of the day if you say 'los vi' you will be grammatically correct and approved the RAE but if you say 'les vi' you will technically be breaking a grammar rule but at the same time you will be in the good company of numerous native speakers from throughout Spain.
I hope that helps somewhat.
I agree with Kiwi's explanaiton.
I'd suggest looking into what's called "leísmo". Kiwi touched on it, but essentially there are speakers (the Madrid area in Spain for instance) that will use "Le(s)" in place of "Lo(s)" even though it's not grammatically correct.
Understanding if you come across leísmo form natives can help contextualize and better understand which pronoun to use. Because honestly, who do you know that speaks flawless English? If you're learning from people, they sometimes make mistakes or speak ungrammatically. A learner has to recognize these situations and learn accordingly.
