One way to make "that's nice" less dry is to add some enthusiasm or emotion to your tone of voice or facial expressions when saying it. You could also elaborate on why something is nice or express genuine appreciation or gratitude. For example, instead of just saying "that's nice," you could say "That's so lovely, thank you for sharing that with me" or "I really like that, it's so thoughtful of you." Adding personal touches and showing genuine interest can make the phrase sound warmer and less dry.
