Between the two you have, I would also second a look at the IS300. Its build quality is 10x both cars and is also a zippy fun little car to drive. Calgary Lexus also has the best service from any dealer I have ever been to (Acura / Infinity and BMW).
The g35 is the worst daily driver to possibly buy. Its expensive on gas, has no trunk / back seat making it useless to put things in, is not easy to drive around in manual if in the city and repairs are pretty expensive.
Cannot say much for the 325i except it will be underpowered compared to the g35. Repairs and maintenance are also expensive, not to mention you have to deal with the fine people at Calgary BMW.
"I believe that banking institutions are more dangerous to our liberties than standing armies. If the American people ever allow private banks to control the issue of their currency, first by inflation, then by deflation, the banks and corporations that will grow up around the banks will deprive the people of all property until their children wake-up homeless on the continent their fathers conquered."
-Thomas Jefferson 1802