As a special bonus, I thought I'd throw in a slightly more complicated Son House tune that also happens not to be in the key of E. This is my version of "Empire State Blues," a Son House classic (key of G). The recording that I arranged this from had 2 guitars, so I've had to make some small adjustments, but on the whole I think it's pretty true to the original.
The intro run (bars 1-4) is classic Son and you'll see it in other songs of his such as "Jinx Blues". I like it better in this song, because this is a song about a train and the intro gives it that "train" feeling.
The part in bars 5-8 forces you to really stretch out your hand to play the G bass while hitting the high notes of the G7 chord thusly:
Now that your tendons are hurting, you understand why a lot of this stuff is played in E or A -- you can play the bass on open strings and avoid the stretch.
After a couple of bars of C7 (bars 9-10), we have a nice little blues-scale run that reminds us of a train once again in bars 11-12. Again, I really like this one. Finally, you can play around with the turnaround at the end and find other stuff that works for you. After the turnaround, go directly into Bar 5, skip the intro (I only replay the intro if I forget the words to give me time to think!).