Good morning M.!
I recently flew for the first time with my 17MO daughter, and it went fairly well. Some things that I didn't expect were that the "liquids" prohibition is a PITA!! :( Whatever your daughter drinks, you'll HAVE to buy it IN the airport. I bought two 8- or 12-oz bottles of whole milk for $4. I wasn't too happy, but that's the way it is. (Unless you nurse, and then rock on! since at least they can't take THAT away! lol)
Also, I have flown a lot in my life, and something I've come to realize about my own ears: if I'm going up in elevation (say a coastal state to a mountain state), then my ears will be fine, they clear as soon as I'm off the plane, very little pain is associated. However, when I go from higher elevations back down to coastal ones, back to sea level, my ears don't clear for DAYS. It's VERY painful for me on the plane's descent into a sea level (ish) airport, and then the pain subsides by the time we land, but I have foggy hearing in at least one ear for 2-4 days afterward. Babies have sensitive ears, be aware this could happen to her too. :)
Spend lots of time in the aisle letting her stand and bounce, and if you're comfortable letting strangers hold her, pass her around if they want to hold her - it'll distract her, five minutes at a time, and the flight will fly by! :) Best of luck!!