So will I notice a difference when taking pictures between a 32 gb 90 mb/s and 64gb 30 mb/s? does the mb/s make a difference from taking one picture to another? does it write to the card faster, so when I try to take a new picture, the camera wont say busy?
30 mb/s is more than sufficient, even for video. I use the cards to shoot HD on the 5DmkII all the time, even using older cards. You might hit the card's 30 mb/s limit only if you do a lot of continuous shooting in burst mode, as cin19 pointed out.
On the flipside, faster cards with a suitable card reader also result in faster transfers to your computer.