Magandang Umaga
Magandang umaga sa inyong lahat!!! Magkaroon Ng Isang Magandang Araw! :)
We don't say <em>"Have a nice day!"</em> in Tagalog, thus, we don't have direct translation for that phrase. However, if you want to wish somebody a nice day, just say <em>"Sana'y maging maganda ang araw mo."</em> which literarally means:<em> "May you have a nice day."</em> But really, it's too mouthful. So my advice just say <em>"Magandang umaga/araw sa inyong lahat!"</em> - that's already understable that you're wishing somebody a nice morning or day.
Phew! That's a little lengthy but hope I helped you. :)
Magandang umaga rin sa 'yo.