I want to make collages of all our travels over the years then print them on canvas.

Can anyone recommend a good, easy to use collage maker for digital photos? I'm happy to pay for one if it's a good program. I need something that will upload photos at high res so they are still clear when printed on canvas.

I envisage the collages containing around 70 photos each and being printed on canvas of around 80cm x 60cm.

Any suggestions would be great!