You should tour both hospitals and interview their labor directors. I hear OP Regional is very very nice and my sister is about to become an labor nurse there. SM is also very nice - but my impression (what I've heard from other women) is that it's kind of a "baby factory." Meaning, you will be pressured into an early epidural and you will be c-sectioned if you don't deliver QUICK.
A good friend of mine was threatened with a c-section after laboring there for ONLY FOUR HOURS!! The baby was not in distress and neither was she. And this was her 3rd child! She had a history of a certain pattern of laboring, and still they threw that at her after only 4 hours. Pretty outrageous.
Depending on what kind of birth you want (that is, how natural, how medicated, etc...) SM might not be the best place. This being your first, you should really be on the same page with your OB about how long you can labor without them coming in, scaring you, stressing you out, pressuring you into a c-section.
I found the staff at St Luke's Plaza to be incredibly supportive and flexible when I had my first. They really tried hard to get the baby out - but I ended up with a very necessary c-section. So I'm not speaking from a super anti-c-section perspective -- but as a first-timer you should definitely beware that this happens in the cushier hospitals. Best of luck.