I'm usually on rhythm electric, and sometimes on lead electric, with my wife being the primary bassist. I do get to fill in for her from time to time, and I really look forward to those times; mostly because I love playing her 5-string Ernie Ball! What a great instrument!
We've added 'Break Free' by Hillsong into our rotation, and man, what a great bass line in that tune! My wife played it today, and did a great job with all the movement in it!
I agree with previous comments: The better the drummer, the more fun, relaxing, and sense of creativity I have playing bass.