When it comes to traditional, hard-driving bluegrass, that played by Bill Monroe and The Bluegrass Boys in late 1945-1947 when his group included Flatt & Scruggs, is my all time favorite and "started it all". If you want to have a great time practicing, learning, etc. try jamming with your favorite band.
If you have Windows Media Player on your 'puter, you can adjust the playing speed of a song between Fast, Normal (recording speed) and slow which is about half speed.
So pick a band, select a song, play the song and play along with your instrument to determine the key the song is in. If the recording speed is too fast, slow it down. If that doesn't work, pick a slower song. Learn the rythm.....then try to play a lead.
You will be amazed after doing this a few times at how much faster you can get into it and it is highly energizing and promotes practicing.