Chúc bạn đi vui vẻ

Yes, if they are going to a meeting or a different location. If they are just starting their shift at the same place as you, 'Chúc làm việc vui vẻ' is better.

'Vui vẻ' is a bit more descriptive and warmer. 'Vui' is just 'happy,' while 'vui vẻ' implies a cheerful atmosphere or state of being.

If they look similar to you, 'bạn' is safe. If they look older, use 'anh' (male) or 'chị' (female) to be polite.

Yes, it's a very polite way to see a guest off, especially if they have a long drive home.

Absolutely. It's a standard way to end an email to a colleague who is about to go on leave.

Simply say 'Cảm ơn bạn!' (Thank you!) or 'Cảm ơn, mình sẽ gọi cho bạn sau.'

In this context, yes. It refers to the act of traveling or moving to another place.

Yes, it's universal across Vietnam, though the pronunciation and ending particles (nha vs nhé) vary.

Yes, but you might add 'trăng mật' (honeymoon): 'Chúc hai bạn đi trăng mật vui vẻ!'

'Thượng lộ bình an' is formal and focuses on safety; 'Chúc bạn đi vui vẻ' is casual and focuses on fun.

Yes, use 'Chúc con đi vui vẻ' or 'Chúc em đi vui vẻ.'

Usually not. It's reserved for trips that have a 'destination' or 'event' feel, like a trip to the mall or a movie.

Yes, it's very common for people moving abroad for study or work.

Young people might say 'Đi quẩy vui vẻ!' (Quẩy means to dance/party hard).