Ok, I have to admit that I am kind of an accessory nut. Shoes and bags have always been a weak spot for me so it has been no different concerning bags for my dog. I have the Kwigy Bo in a small. My Gracie is 5 pounds and fits in there nicely but she can't really turn around in it and she dislikes having to lay down and be zipped into it. Of course I did not start putting her in it until she was already a year old.
I agree with the person above about getting a large for the dog's comfort. It may seem big at first but with blankets and such in there it won't be a problem. I am still searching for the perfect bag. Ventilation is important especially in the warmer months. The advantage of the Alex and Alexa is the fact that your pup is hidden from sight should you need to take it in an area where you might not want to be seen with a pet.
I am already in the process of having a collection of pet carriers. The next on my list is:
Lizzie Pet Carrier - Petfavors.com - The on-line store for pampered pets. Designer pet beds, pet carriers, outdoor cat enclosures, pet strollers
It's made by Backbone. I actually found it on another website for $87.00 so I think I'll probably get it for use this spring.