San Francisco Birth Center

We faced this exact dilemma, interviewed a bunch of doulas/the midwives (at SFBC), and ended up going with no doula. Our rationale was, one of the major benefits cited was that the doula would provide support to my partner/be an extra pair of hands. But my mother was also visiting, so we didn't need that. 

Well, in the end I was in labor mostly at home--got to the birth center just 40 minutes before the baby came out. And if I could do it again I think having an extra person would have been useful, especially since my labor was overnight, and everyone involved was very tired & needed sleep. I did not feel it was important to have a doula once we got to the birth center, though ymmv depending on how long you end up being in the facility.

That being said, having no doula was definitely totally OK because we had read the book The Birth Partner and so were relatively prepared, plus also had my mom around--if we hadn't had both of those things I think it would have been a much worse experience. Also, the few contractions that a midwife helped me with were noticeably smoother and more pleasant than the ones my husband helped me with, which were also better than the ones my mom helped me with--so experience+strength can definitely make a difference to your comfort.