Good question! I have one tomorrow, too, but it's just with my Family Practice dr (need a pap, so I figure I'll get it out of the way and see what she has to say about the dr.s in the area - we moved up here a year ago).
There are a ton of questions you can ask, but they should be geared to your life, wishes and concerns. Maybe some possible suggestions:
How long do they consider "normal" to conceive before they will intervene?
Frequency of prenatal visits?
Sonogram on site? If not, where to go for sonograms?
Will you deliver my baby or is there a rotating staff of Drs. who I have to see?
Will you always be doing my prenatal visits?
Which hospitals do you have priviledges at?
Opinions on c-sections, inductions, pain meds, etc.?
Thing to avoid while TTC?
When should I call you after I have gotten a BFP?
Will you monitor my HCG and progesterone levels during the first few weeks?
Just a few suggestions. Hope it helps! Good Luck TTC!!!! Come chat at the TTC Newbies 1+ month thread!