Are there hybrid cables - solid and stranded?

Not sure what you are asking. Solid core simply means a single strand. If you are wondering if someone is making a cable with a single conductor insulated seperately from many conductors within in the same cable than yes there are hybrid cables.

I'm pretty sure Kimber Select does.

Some speaker wires are thick solid one strand, while others are thin with many many strands - are there cables that combine the best of the both worlds is my question.

Thanks a lot for all the posters so far!
Please keep them coming...

Audiolabryrinth,
I believe DNM was a big proponent of solid core cables before Tara Labs.

I'm pretty sure the various cable companies offer every conceivable configuration of solid, stranded and Litz wire, shielded and unshielded, to meet our demands, even the ones we didn't know we had :-)