The bride has asked for this cake to serve 400. Looks to me like the taller tiers are maybe 4 layers. Any help?[/img]

looks like a 6/8/10/12/14, with the 8 and 12 being what I refer to as "half talls." Just use the Wilton charts for serving sizes, but you will only get half as many servings from the half talls.

Anybody have any ideas?

Well, assuming Leah is right (which I'm sure she is) and not accounting for the "half talls" giving you less servings that's only about 250 servings at most. I would suggest some lovely kitchen cakes to make up the additional servings needed.

That bottom tier may be a 16". The dimension looks wider than the others.

Thanks so much!!