"Los extraño" vs. "Les extraño"
If i want to say "I miss you all" as in "Extraño a ustedes", would i say "LOS/LAS extraño" or "LES extraño" ????
5 Answers
It should be "los extraño," unless all those people you are missing are female, in which case you would say "las extraño." You are replacing "Uds." with a direct object pronoun, like "it" or "them." When you replace a specific group with "them", you use "los" or "las," just like when you replace a specific thing with "it."
Hombres y Mujeres: Les Extraño. ("Como les extraño")
Les is used for "them" regardless of gender.
Maybe the following will help.
Indicating that a person "received" some emotion, sensation, result or impression: El trabajo le abruma. (The work is overwhelming to her.) Le gusta el programa. (The program is pleasing to him.) No voy a explicarle las teorías. (I am not going to explain the theories to you.) Les obligó que comer. (He forced them to eat.) La decisión le perjudicó. (The decision harmed him.) Les es ventajoso. (It is advantageous to them.)
Indicating a loss of something.: Le robaron cincuenta euros. (They took 50 euros from her.) Le sacaron un riñon. (They took out one kidney from her.) Le compré el coche. (I bought the car from him or I bought the car for him.) Las inversiones le devaluaron. (The investments lost money for him.)
With various phrases using hacer or tener: Les hacían feliz. (It made them happy.) Les tengo miedo. (I'm afraid for them.) Le hizo daño. (It hurt her.)
When a verb affects a body part or an intimate possession, particularly clothing. In such cases, the pronoun is seldom translated to English: Se le cae el pelo. (His hair is falling out.) Le rompieron los anteojos. (They broke his glasses.)
With certain verbs to indicate sufficiency or insufficiency. The pronoun isn't always translated to English. Le faltan dos euros. (She is two euros short.) Les bastan 100 pesos. (A hundred pesos is enough for them.)
When making requests or addressing someone: Le pidieron dos libros. (They asked her for two books.) Le exigió mucho dinero. (It required much money from them.) Les dijo que es peligroso. (He told them it is dangerous.)
almost literally,
les extraño = (to) them I miss
los extraño = you (plural) I miss.
and ditto what mcwalters said 
Los extraño.
Singular vs Plural.
Mujeres: Las Extraño (a ellas). Las extraño mucho.
Hombres: Los Extraño (a ellos). Ni los extraño tanto
Mujer: La Extraño (Ella). La extraño muchisimo (mucho).
Hombre:Lo Extraño (Él). Ni (No) lo extraño.
Hombres y Mujeres: Les Extraño. ("Como les extraño")
