I'm getting tired of sitting in front of my computer, so I won't read all the replies you got. I just noticed that no other women replied, so I'll give you my opinion.
C is very hard for me to sing in too, and D is great. If an accordion player with whom I'm going to be singing can bring only one accordion, I'll choose D. However, there are a few songs that are better for me in C, and I also like E sometimes. All the same, go with D. That's where the majority of mine are, and I think most women feel the same way.
If you have a D box, you can use some software like the Amazing Slower Downer to not only slow the music down but change keys. This is for CD's and not video, DVD's.
So if the music is in C you can change it to D so you can play along. With DVD's You'll have to make an mp3 file and then bring it into the Amazing Slow Dower
to change keys.
Hind sight is 20/20. Linda would have been better off getting the "D" accordion! She would have been one of the few amongst the many, which would have automatically made her special. Little did she know that some of the best songs available now on youtube were made with "D" accordions. She would have been a stand out from the crowd! Besides, being a female, she could have easily just asked to borrow one of the thousands of "C" accordions floating around at the jam sessions and decided whether or not she liked the "C" accordion. Also, notice the particular preference by "Sarah Savoy" for the "D" accordion in her post on this thread. It couldn't be that her dad is also fond of the "D" accordion now would it? I'd like to go back and figure WHO THE HELL decided the "C" accordion was going to be the standard for beginners and give him a mighty hard yet well aimed kick to the ball sack! The "D" accordion....every bit as important as the "C" accordion, just hardly anyone knows about it yet.