For a wedding cake for 150 people, I'd do 4 tiers: 6".8",12",16", is that consistent with what you would do?

Also, should the client decide on stacked or pilars or should you? I've had someone call with an order for a wedding cake for 150 people, they only said they want it simple... Should I decide on everything else? (They've picked the filling, batter and icing).

This would be my first!

Thanks!!!

I would ask what the color scheme is for the wedding. I would definetely ask for more details. Show em some of your pics of ones you have done and see which one they like the best. Ask if they want to stacked or pillared because I think if they want it pillared you would have to charge them a deposit on the pillars and plates. (don't know if you use plates and plastic dowels for your stacked). I would try to get as much info from the bride as possible. Just to cover my butt. If they for some reason (gawd forbid) don't like it. You can point to the contract and say, "this is exactly what you specified."

And YES, get everything and I mean everything in writing.

"Something simple" is very vague and could mean different things to different people. For an event as important as a wedding, I would show samples of both tiered and stacked cakes from my portfolio or cake decorating books.
What is the color scheme for the wedding? What are the flowers/colors used in the bouquet Where is it being held A room with high ceilings would need a taller cake, and you might then suggest pillars. Is it a theme wedding? Does the bride go for simple but formal or simple and country or clean lines and modern. I could go on and on. Make sure everyone agrees to your final customization of the cake. Get everything in writing.

you need more info that is for sure.... if they lay it all out then they can't complain at the end when you have followed their requests.

In regards to stacked or tiered you can guide them based on your ability... I think its a personal taste thing... personally I loved stacked but know lots who prefer tiered so ask them to choose.

I am sure it will be beautiful because it will be made with love.