Do relationships improve or reduce your creativity/productivity?
tsally: It depends.  I have heard from the graduate students at my school that the ones with wives work much harder and usually always finish on time.  I imagine this is because they probably aren't allowed to spend more than 40 hours a week at school, else their wives would kill them.  Near limitless time (which most graduate students think they have) can be a huge burden.  I have no idea how this would translate for a startup, but a marriage can be a huge net gain fora  PhD student.