Here are few random thoughts on what I've found works really well with the Car Radio...
I've set up Car Radio buttons to have four different types of music streams:
1. Broad genre stations: Rock and Pop, Classical, Jazz, with variety set to low. These are great, Pandora-style genre stations which feature my 4 and 5 star tracks.
2. More specific stations using the Style and Instrument tags, great for New Orleans or Blues Rock, etc.
3. Artist based stations, Composer based stations
4. Custom Smartlists: Recent Albums in random order; Classical Instrumentation based album lists (Cello, String Quartet, Orchestral Works with shuffled albums in track order), "Main Rotation" Favorite album Lists.
Three of the above types use Play Doctor, and they all yield very different lists from my collection. It's fun to mess around with new inputs and settings and get better results.
It's taken me awhile to realize how so flexible the tagging/Smartlist system can be, and after a few years of using MC I still feel like I am only getting started. Having quick access to Smartlists/playlists on the Playing Now screen is a big help...I use them a lot more since Car Radio started.
Many thanks to recent Interact posts by Matt, MrC and Glynor and many others on tagging, expressions, Smartlists, and Play Doctor. It's great to have such great support here for technical help and lots of inspiration for new ideas on how to use the program.
If anybody else has some good tips for setting up good Car Radio buttons, feel free to post below. Thanks!