Formal:
* "Cela me semble excellent." (This sounds excellent to me.)
* "C'est une très bonne idée." (That's a very good idea.)
* "C'est parfait." (That's perfect.)
Informal:
* "Ça marche!" (That works!)
* "Génial!" (Awesome!)
* "Super!" (Great!)
* "Pas de problème." (No problem.)
* "D'accord." (Okay.)
You can also add a personal touch by using phrases like:
* "J'ai hâte!" (I'm looking forward to it!)
* "C'est parfait pour moi." (That's perfect for me.)
* "J'adore l'idée." (I love the idea.)
The best choice depends on your relationship with the person you are speaking to and the overall tone of the conversation.