Como estas tu? vs. Como estas?

When would one term be more appropriate then the other?

Hola GRINGO1. Both expressions mean the exact same. The "tu" on the end of ¿como estas tu? its already implied. You can find the clue in the way the word "estas" ends...for example. Yo estoy El/ella está Tu estas Ellos estan Nosotros estamos As you can say the verb "estar" changes depending on the person...so you CAN`T ask "Como estamos tu?"...cause "estamos" is only used with "nosotros" or we. In this case the correct question would be "¿Como estamos nosotros?" but again, without the "nosotros" the question will still make sense, again, it is already implied :) I hope i was clear! Mucha suerte, saludos desde México :)

Muchas Gracias!

Gringo, you'd use tú for emphasis, since there is no ambiguity here. Imagine this dialog: A: Hola, Come estas? B: Bien. Como estas *tú*? It would sound mechanical just repeating the same phrase. In English, the emphasis might be like this: A: Hi. How *are* you? B: Fine how are *you*? The stress placed on *you* in the reply is the same using *tú* in the first dialogue.

I just had an "ah ha" moment Raymot, thank you!

Excelente!!! saludos desde Mexico amigos mios!