Check out where I put the 728 4 unit text link under the navigation menu http://www.bmwleasedeals.com/ am I violating any TOS with my adsense account?
It looks pretty good since there is a big "Ads by Google". But you might have a problem because it looks like a part of your navigation column. Google might say you're trying to push people into clicking on your ads. Put up a barrier between the top of your column and your ad if you can. Like a line separating the two or space the ad and column even more than it already is.
Couldn't care less. People who like to push the rules generally get banned. It's your money so go ahead and test them.
Nice website. About the adsense layout as long as there is a difference between ads and content + presence of adsense by google it is safe ,I think.