We took our 3 daughter when she was 9 weeks, it was a breeze, she was amazing. I wore her in the sling 99% of the time (we have very few pictures, because she was always in the sling). I nursed her everywhere we felt like it (even on some rides when I could).
I would leave it up to mom, if she feels good go. My first baby, there is no way I could of gone, but after the 2 and 3, I could of gone within a week. I jumped right back into life after the last two, I had no pain at all when we left the hospital (we discharged at 24 hours old too). But, with the first I felt knocked down for weeks.
The baby stations were great, but, we did not use it the first trip (when the baby was 9 weeks). She was portable, we just changed her in the stroller, (it was december, so it was not hot), ate when we wanted and had a great time.
Your older kids are much older too, where they will not depend so much on you. When we took our little one, her sisters were almost 2 and almost 3!! (they were good too), but I could only imagine with a 7 and 9 year old how much easier it would of been.
We are also not scared of germs, so for me that was a nonissue. The noise did not bother her, she rode everything without a height restriction (and most of the time she stayed in the sling through the ride). Taking a baby was easy!