* Tengo muchas ganas de ir a la gran fiesta: This is a very common and versatile option. It translates literally to "I have many ganas (desire/urge) to go to the big party."
* Espero con ansias la gran fiesta: This translates to "I await with eagerness the big party" and is a more formal and slightly more emphatic option.
* Estoy deseando que llegue la gran fiesta: This translates to "I'm longing for the big party to arrive" and expresses a stronger anticipation.
* Muero de ganas de ir a la gran fiesta: This is a more informal and expressive way to say it, meaning something like "I'm dying to go to the big party." It's more suitable for close friends.
The best option depends on the context. For most situations, Tengo muchas ganas de ir a la gran fiesta is a safe and appropriate choice.