Watch the Sonata No.1 for Solo Violin online guitar lesson by Tony Smotherman from Classical Flatpicking Explorations
This piece is in G minor and works through quite a few arpeggio sequences. Although not very difficult once fingerings are worked out, I like that this piece focuses on fingerings for the arpeggios which can be applied to many other things. Be sure to work through the changes at an even tempo to get the timing down.
I also like how melodic this piece is, as it makes sense musically. Once you hear the theme, it's easy to follow along to get the feel of what Bach was going for. This sounds great on electric as well with the distortion cranked.