I've used mother's clay bar before with great results. The bar will be enough to clay the whole car. Make sure you do it in a shade so the lubricant doesn't dry so fast from the sun. Also make sure you fold and kneed the clay as soon as it gets dirty. BTW becareful with the clay if you drop it, it's useless because it'll pick up lots of nice sized particles from the floor that will scratch your paint.
Also like KKSigua, I totally love zaino products. They also have a new wax, think it's called Z-cs basically it's a clear bottle you just spray and apply with a cotton pad and let dry. check them out at
www.zainobros.com
I've used meguiars wax in the past, they barely last more than a week.