I am doing a 14", 10" and 6" cake in which the tiers are not centered, but closer to the back. I need more servings than this, so off to the side of the main cake I will have a 10" and 6" decorated the same. I have never done 2 cakes like this before- is there another route I should be taking or will this look fine? Thanks for any ideas!

If it's a wedding cake, what does the bride think? Does she like this type of setup?

She showed me a picture of a 3 tier cake, and I told her I thought I could do it 4 tiers and get the right number of servings. After looking at my pans I realize this is impossible. This is the only possible solution I think. The bride is pretty indecisive about everything and her wedding is Saturday.

I think it will look fine, but it's not my opinion that counts... if she's okay with it, then there's no problem to solve.

If she's not okay with it, here's another possible option... I assume the serving goal is 166 (not including the 6" top anniversary tier).
You could still do a three tier--16" x 12" that serves 156 (not including an 8" top anniversary tier).
I don't know what the impossibility is about your pans... perhaps you don't own a 16" round??? Good luck with this bride.

I'm doing it as a gift- she's the daughter of my best friend and I really want her to have an awesome cake. She'll be fine with what I decide to do, I just wanted to know if this set up would look okay. I'd thought of the 16", but not only do I not own one, they just seem well not so dainty LOL. I appreciate your help!

You could always just keep the other cake in the kitchen and serve it when with the rest of the wedding cake.

Here a few examples of how it might look:

http://cakecentral.com/gallery/2149662

http://cakecentral.com/gallery/2152411

That's very pretty!