A lot of the things don't translate well - or the English word is the word. I won't tackle all of them:

Has my seat been upgraded?
Has my room been upgraded to a suite?
Could you upgrade my room to a suite? (or room with a view)

Economy Class - Clase Basura
Business Class - Clase Ejecutiva or Business (depending on the airline)
First Class - Primera Clase

Starwood Preferred Guest Platinum/Gold Member - Platinum / Oro (the SPG hotels will use the English metalic name)
Priority Club (Royal) Ambassador - Mejor que sos

Reservation - Reserva
Hotel Room - Habitacion
Room rate - Tarifa
Suite - Suite
Nonsmoking room - Hab. no fumadores
I am allergic to smoke - Tengo alergia a humo.

Do I have access to the Executive Lounge - ¿Tengo acesso a Salon Vip?

(My computer just flipped and some of the text disappeared, I'll have to reply to some later.)

And for Argentina, please remind me how to conjugate to vosotros, such as:
hablar
comer
venir
ir
jugar (and others where the root changes)

Argentina DOES NOT USE vosotros. Argentina uses vos, instead of tu. You (plural) is always Ustedes.

In a nutshell, most irregular verbs become regular (almost) in the vos form, with an accent over the last vowel. (I'm not going to remember all the codes for the accents now, just remember, accent over the last vowel).

Ejemplo.
Poder - (Vos) podes
Tener - Tenes
Contar - Contas
Querer - Queres

Ser becomes "sos" - ¿Vos sos estadounidense?"

The LL is generally pronounced like a "sh", as is a "y".

Yo llegue a la calle con una toalla).
(sho shaygay a la cashay con una toasha)