We drove both the Mazda6 and the Mazda3 and decided we preferred the suspension of the 3. We don't do much freeway driving and found the 6 too 'soft' with a tendency to wallow on our twisty local roads.
We're very happy with the 3 but I won't give up the Miata.
FWIW we paid 17,000 euros (about $22,000US) for the base model, 1.6 litre, no leather, no nav, no CD, no sunroof, 3 year warranty. Your deal sounds good.
I had always heard that an oil change after 600 - 1,000 miles was a good idea for a new car to flush out metal shavings or whatever. The manufacturer recommends the first oil change at 10,000 km and when I asked the dealer to do one earlier, he said it wasn't a good idea. According to him there's a special oil in the new engine which helps run it in and this should not be replaced until at least 8,000 km. This is new to me. Has anyone heard of this?