I've been asked to make a cake for a graduation open house for our friend's son. I have not made a graduation cake before. They are expecting around 125 to be in and out throughout the day. They would prefer a tiered cake to sheet cake. What size cake do I make? Do you figure it the same as a wedding? More or less?? Any suggestions from those of you who have done graduation cakes would be greatly appreciated

I'd go w/about a 14, 10, 6 for 125 servings.
If they start the serving from the top down most people will get to see most of how itr looked. OR cutting from the back go about 1/3 of the way on each tier before removing the top tier to finish cutting it ect.
If you use sqs you will get a few more servings.
Ooohhhh why not make a smaller tiered cake (2 tiers?) and flank it by a sheet or sq that would be served 1st. That way the tiered w/been seen most of the night before it needs to be served.

Thanks! That's kinda what I was thinking. I just wasn't sure because unlike a wedding, people are coming and going and some eat and some don't. I want to have enough cake but not leave them with a whole bunch left over.
I like the idea of a side cake--maybe I could even do 2 or 3 small cakes around a 2 tier?

Sure you could use 3 8" rounds - for about 75 servings before going to the tiered.
Yes, w/an open house there might not be many that will eat. Where I was *everyone* had their open house just after grad ceremony and they ordered a full sheet (24x18x2).