Playlists or Genre Tags....what works the best?

Hi

When categorising a subset of music that will be played together...what works the best? Playlists? or Genre Tags?

On my current Squeezebox system....tags seem to be more efficient.

For example....

I could tag my music with 'His' and my girlfriends with 'Hers' and then play the Genre, or I could create 2 different playlists and add the tracks to them.

Thanks