We always book thru Carnival ....biggest reason is: if your excursion is delayed for any reason---the ship WILL WAIT on you!
If you book via someone else and you are delayed...they will NOT!
The choice is yours...people do it both ways and most times I'm sure they make out fine.
but, this is just our opinion
Welcome onboard and you guys are going to be cruise addicts like the rest of us!