Is it have a good week or have a great week?
Have a good week means the same thing as have a great week. The adjective “great” means “wonderful,” whereas “good” means “pleasant” or “generally positive.”
Both expressions are useful when you’re communicating with someone on Monday. They only work when you’re unlikely to communicate again before the week is over (e.g., “I hope you all have a good week, and I’ll see you when I get back on Friday”).
QuillBot’s free Paraphrasing Tool can help you with word choices when you’re writing emails or other correspondence.