Congratulations on your pregnancy
My husband and I are both 6ft also, and our 2nd was a large baby (for a girl)... 9lb4oz. She still fits small itti's very well and they're known to be small rise, so I wouldn't necessarily worry about getting something high rise for a newborn. It'll help too if they're lower at the front for the first couple of weeks so as to not interfere with the cord stump. Btw, i wouldn't really recommend itti's for a new baby - the runny poo isn't contained that well, this reply was simply to point out that something low rise is perfectly fine even though we expect her to be tall like us.