I think Nia is really pretty! It's one of those names that I don't think I would use myself but would like on someone else's child. My only drawback is that is sounds so similar to Mia that my brain wants to just say Mia. Either way, Nia is still a really nice name, and I could even see it as a nickname for names ending in -nia. A few I've found: Alania, Antonia, Xenia, Zinnia, Imogenia, Petunia, Junia, Serenia/Selenia, Virginia, and Lavinia (my favorite)... there aren't a lot of super usable ones, you so might be best off with just plain Nia.
Nia Claire is just lovely, but here are some other options if you're still looking:
Nia Juliet(te)
Nia Faith
Nia Peneleope
Nia Willow
Nia Grace
Nia Vivienne
Nia Rosaline
Nia Rue (I love the sound of it, but it's so short for a combo)