What novels balance cosmology and philosophy with strong character writing?

[SamuelR]

I've just finished the "Remembrance of Earth's Past" trilogy and I'm craving more ambitious, idea-driven science fiction novels that explore big cosmological and philosophical concepts. I love the genre when it uses its speculative nature to examine humanity, but I sometimes find the prose in harder SF a bit dry. For fellow readers, what are your recommendations for novels that masterfully balance profound scientific or sociological ideas with compelling characters and elegant writing? I'm open to both modern authors and foundational classics I might have missed, particularly any that offer a unique perspective or a mind-bending narrative structure that stays with you long after the last page.