Sorry, Jim (and others)
Since I don't know enough to ask an intelligent question, I may not be able to further clarify this. Since it's a surprise gift involved, I can't ask my wife to help. The only thing I can say is that she played popular America music (i.e., Pop category of music) when she was young, on the keyboard accordian. And what she would want to play would continue to be melody, with full chromatic capabilities. That's about the extent of what I can add.
Bob Tedrow's location reminds me that a couple of years ago, when she began talking about the concertina, she found someone in Alabama who sold or had further info on accordians and/or concertina. But, again, this is too vague to be of much value.
I'm assuming from what I was able to get from reading, is that the English would intuitively seem to be the best gamble. (and, for me, a gamble it is). But if the differences are truly as distinct as the "fiddle, banjo, and guitar," then I'm probably in a hopeless quandary. (kinda like playing in the Futures money markets when you don't know what you're doing)
Again, sorry for not being more informed. Since I just joined the forum, I'll try to go back further in the archives of the forum, if the database allow. Thanks again.