Patience and appropriate expectations.
We brought our (then) 3 month old back in April. It was a fantastic trip and honestly he did such a great job, but we knew that the trip would be different from our previous ones with our older kids. We definitely slowed down our pace.
Our son spent time between his stroller (a City Mini) and the carrier (an Ergo).
We used the babycenters since I am nursing. They are a great place to get out of the heat and relax with little stimulation. I did have to nurse in some funny places (like on POTC) but if a babycenter was nearby, I went there, lol.