We just came back from a plane trip/mini vacation with our 3 kids (4, 2, & 6 mos.)
What I learned this time around (we've probably flown with a baby about 10 times):
BACKPACK is so much easier than the diaper bag for getting on/off the plane (You can always pack an empty diaper bag in your luggage if you want it for use at destination--I didn't need it)
Wear your baby in a carrier to board the plane. I have an ERGO, which is super easy to put on, even if in a hurry.
Bring a clean outfit for her & a clean shirt for you in case of a spit-up or diaper blowout on the plane.
If you will be getting her a seat, she will have to sit next to the window. If you will have her on your lap, you will need to check her carseat, but can do it at the gate. You will get a bright colored "Gate Check" tag to put on her carseat and/or stroller, and then you leave it at the end of the hallway, just outside the door of the plane.
Bring her birth certificate (required by the TSA for all un-ticketed babies under age 2).
Bring her favorite blankets. If you use white noise at home, you might need it at the destination as well. I'd bring only 1-2 containers of solids on the plane, and buy the rest at the destination. Since you will only be there for 3 nights, I'd go ahead and pack enough diapers for her for the stay.
Ask the resort to have her crib/pack & play already in the room when you get there, so that if she needs a nap right away you can put her down.
The most important thing I have learned over the years is to be as hands-free as possible!! Backpack & infant carrier - I mention it again because this trip was the first time I used them, and it was by far, our easiest (even though it was with 3 kids.) Use the family-line at the TSA checkpoint. Have slip-on shoes for you, so you don't need your hands to put them back on again. You will have to pass her stroller & carseat through the x-ray at the airport, so you or your DH will need to carry her through the line.