Check this page: http://www.linuxphoto.org/software.html
I am using Gthumb for photo management and I do not
view raw files. I cannot give you a recommendation, you should try the various programs yourself.
However... I think cr2 is a Canon 400 10 Mp image, right? Converting the RAW files for viewing will take time, especially if you have 100 files in that folder.
What I usually do is rename the Canon .thm files to .thm.jpg once they are in the folder. Granted, the colors are way off and the picture is not autorotated, but it gives me sufficient idea of which picture is which. So I can open it with UfRaw.
BTW, I am using UfRaw for RAW conversion. Since it allows a zoomed view and cropping in the newest version it really became a useful program.
RawTherapee offers much more features, but is way slow. If reactions in the picture are 500 ms lagging my mouse actions, I develop a RSI in 30 minutes. RawTherapee offers noise reduction, which UfRaw does not. But I also exprienced that settings like color and brightness suddenly moved to extreme positions and I had to quit the program and restart processing -- losing all my precious settings for that picture.