Tips for managing large music collections for offline play?

[asdfasdfkl]

I have more music than fits on my mobile devices (Walkman and smartphone). I initially generated "Master" playlists for each music genre, but they are too large to fit in offline mode. Then I created "Mobile" lists with just a fraction of the songs of each genre.

Now my issue is how do I manage tracks on those Mobile lists. Best case would be to be able to automatically select X number of tracks from a Master list, and copy it to the Mobile list. Now I do it manually, but there's no way randomize which songs to pick, or to ensure I rotate all the songs as far as I can tell.

How do those of you with large music collections manage offline playlists on your mobile device?

[driveflanger]

Hi. This is very subjective but I'll give you my opinion.

Yes, a lot of songs in one playlist could be very unpractical. I mean if I like Rock I couldn't make a playlist with all rock because it will be like thousands of thousands of songs. Being realistic, I'm not going to be able to listen to all of them, even in shuffle mode.

What I'm doing now and since I've been a user of spotify is to make mood playlists. Most of them have around 60 songs and it becomes more manageable. 

If I'm really into one band, I make playlists of each album sorted by year.

If I'm going to india, I make a playlist about raga music.

if I'm going in a road trip. I make a playlist with music that will suit the road trip environment (desert, jungle, etc)

But that's the way I do it and I tend to discover new music.

If I don't want spend time creating playlists, I suggest using the radio feature. It's faster and according to the first track you choose.

[asdfasdfkl]

That's pretty much what I'm doing. But the question is how do I create semi-random playlists for mobile use from a large pool of tracks? Now I order the songs by length, and select random sections of the list which is a decent workaround. But it would be even better if there was a way to order the songs randomly.

Radio feature is not useful when offline, as far as I can tell.