How long will the plane ride be??!! If you are flying over night no problems... since you will be staing so long her sleep will fall right into place.. might be cranky the first day (who isn't!!)... if you are flying during the day.... KEEP HER UP the night before.... I took my one year old to England and I can say that a sleeping child is much easier to deal with than one who does not want to sit in that chair for 8 solid hours (time from Chicago to London). Take a bottle, pacifier, and anything else she can suck on for the pressure in her ears... and pack a bag full of her favorite things.... Long time for her to get bored. Yes it is a hassale carrying all that stuff.. but I used everything I took plus I still had to walk her up and down the aisle... talk about the clouds outside and reapeat over and over yes that's airplane ... books that she can interact with are a good thing.. counting books.. if you are doing cards to help her with her language skills take those....
oh and this may sound funny but if she is sitting anywhere near you at meal time may I recommend a sippy cup for yourself.... think about it.. if she accidently knocks that cup all over you!!!! I took one for me and my two kids and very grateful I did everytime I had to pickup the cup.
As for the nap thing... my first son never wanted to nap.. Once he hit the one a day nap cycle he refused to take one even though he clearly needed one. I realized that if I let him hold off until 3pm he would take one... just don't let her sleep past 5 or 6 at the latest. Give that a shot... and good luck!!
SAHM with a 6 year boy and a 2 year old girl