I would play it safe and get the one bedroom, since your baby isn't actually here yet. Some babies are *very* easy going. Some babies can sleep anywhere, anytime. You can have lights on, watch t.v., do whatever and they snooze away for hours. My daughter was one such baby. She was born *extremely* premature (weighed a pound at birth) and spent nine months in the NICU. While it was a horrible, horrible experience I never want to repeat, I can tell you that when she came home she could and did sleep through anything and everything. Seriously, she would be playing and then just suddenly *zonk*, fall asleep on the floor in the middle of the day with people all over the place, vacuums running, me standing one foot away on the phone .
She never even had her own bedroom until her brother was born, and even now usually cosleeps with us. We very easily could share a studio with her without a single inconvience to us.
Then came "the boy".
We joke and say that all the moon's must align properly for him to sleep. Where DD could sleep anywhere, the boy *must* have a full-sized crib. No pack and plays for him! He also must have complete quiet, and dark, and cotton sheets, and cotton pajamas with buttons and not zippers.
It would be a completely miserable experience to attempt to go anywhere with him in a studio. It really would ruin the quality of our vacation.
Have fun!!!! The first trip with a new babe is always exciting!