The largest cake I've ever done was 4 tiers and I used bubble tea straws and a center dowel rod to support it (and all smaller ones).   This coming weekend I'm doing a 6 tiered cake and someone suggested to me that the bubble tea straws would not be sturdy enough for a cake that big and that I should use all wooden dowels or even PVC.  The tiers are 6", 8", 10", 12", 14" and 16".    Does anybody have any thoughts or experiences on cakes that big?    I'd really appreciate the input!

I only ever use SPS for cakes over 2 tiers - for a 2 tier 6" and 8" I occasionally use bubble tea straws but only if the cake doesn't have to travel stacked. I think straws might be ok on your 6 tier but I just wouldn't risk it to be honest. I mean I know they're strong but that would be a lot of weight. If you can't get SPS in time, go for regular wooden dowels which is what people have been using for years.

definitely use sps (single plate seperator) system.  the dowels come in 4 inch lengths or you can buy the ones that are scored so you can cut them longer, but they will still all be exactly the same length.  you won;t be able to do a center dowel, but you should have to. there are tons of video tutorials to show you how to assemble it but its super easy. a cake that tall just needs to be super straight and the sps will ensure that :) good luck!

i also meant to add, that some craft stores carry the sps plates and dowels (our local hobby lobby does) but if you can't get them in time, then go with wooden dowels. i wouldn;t risk the straws not being able to hold that much weight

Well, I can assure you that they are if you cut and place them correctly. I'm not balancing $1,000+ cakes on something I don't trust. That said, I would use SPS if you are at all concerned about them. I vote SPS all the way for you.

SPS, absolutely. I deliver my cakes fully assembled.

AI have a LOT of experience with cakes that size. Zero problems when using SPS.