Question: I am baking a 3 tier wedding cake for August. It will consist of 2 white layers and 1 chocolate layer in the middle. I am covering these layers with white fondant. Should I rather stabilize these layers with straws or rather wooden skewers?

Answer: 
I have done a couple of 3 tiered wedding cakes. I would recommend using something stronger than plastic straws, mainly for your peace of mind. You will be putting a lot of effort into the cakes and like @Joe said, the straws can be useless if crushed or deflected. If you want to use the straws so that the wooden skewer doesn't touch the cake, you can always use the straws and then insert them with the woden skewers for additional support. Straws and skewers are both easy to cut as well, so there's not much of a difference there either. There are heaps of videos and articles online and you can always ask your local cake shop for more tips and tricks.

Another thing to keep in mind is to use dense cakes like mud cakes to use for stacked cakes, otherwise your tiers will collapse. And please give ganaching a good thought as well. Even though there is extra cozt, effort and time involved, ganaching will make the cakes a bit tougher as the chocolate should harden once set and give very beautiful sharp edges when you fondant.
Having tiered cakes need "pipes" I would say. Instead me explaining the process I could share a link with you. There's this cake "Boss" Buddy Valastro : TLC Star.

<http://www.tlc.com/tv-shows/cake-boss/photos/buddys-sketchbook-season-4-pictures.htm>

He shows number of ways to slice, dice , stand , hang, hold cakes in different sizes, different layers.

PS: not sure what you meant by straws...as straws are quite weak..