Depending on which one you get...  Celltei that is... 
 
I have a couple... They are ALL 100% comfortable! And 100% perfect for you dog!!! Airline approved! And I can tell you that they fly VERY well... I have done 6 flights with mine now... I have the over the shoulder one that you wear with the body of it in front... I also have the one where you wear it like a shoulder bag or purse...with the long handles...  it wears like one of my coach bags does... very easy to wear! and plenty of room for my stuff too! If you are doing a small or xs it is soooo like having a really cute hand bag!! Any bigger and its like an over sized purse... Which are all the rage! And they are dog enough without screaming "look everyone!!!! I have a dog!!!" I only get noticed a third of the time and its mostly cause I am talking to my bag! hmmmm dead give away! 
Best of all.... if you are not totally in love with it... send it back! No prob! they don't want you keeping it if you don't love it! They want you 100% satisfied! So you can rave like me!!! and I have yet to send anything back! lol But its nice to know that I can if I ever needed to! If you order the wrong size! if you don't like the color... or if you just decide you don't like it!  
And the sizes.... you will want to order bigger than you need... be careful... its not like ordering a crate... they DO NOT NEED to stand up, turn around and run circles in it!!! It is supposed to be a smaller space.... If it is a big open space they will get thrown around when you walk!!! Rolling from side to side with each step! I ordered a small... on the Active one.. thats the one strap over the shoulder one... and I can put all three of mine in it! And they are happy! Not cramped... Just my two girls and they have plenty of room... If its just pixie... its way too big!!! I had to stuff one end with blankets when I first got it! I was hoping she would get bigger than she is... but nope... 
So I have 2 three pounders in there and one who is 2lbs and 9 ozs... so almost 9lbs in the small.....   They do just fine!!!  
If you go big, you'll hate carrying it! It will overwhelm your pup, who is a burrower by nature... and it will end up in the closet... 
 
    
Have fun on your trip!!!!! I want to go!!!!!! 

 Post when you decide what your getting!!! Or post a few choices when you narrow it down!!!