I am doing a wedding a cake it will be 14in, 10in, and 6in and I wanted to know how tall each layer should be,I was thinking 6in but I just wasn't sure.Please Help!

It depends on the look you want but typically they are 4 inches. Because they each have a 4 inch difference it might look nice to go a little taller though.

Anywhere from 4 1/2 to 5 1/2 looks nice.

I think 4-5 looks nice.

In general a 'tier' is comprissed of two 2" layers of cake making each tier 4 1/4" tall - the 1/4" being the thickness of the icing.
Now I dare say we don't usually go around measuring exactly how tall our tier ends up being The smaller the tier - like your 6"er - will look taller but it's only (what we call) 4" . I'm sure you have seen/read that in general a serving is 1x2x4.
Most plates used to serve dessert are 6"ers. To put a piece of cake 6" tall on it won't 'present' well. It will look out of place - overwhelming the plate.

4" +/- is pretty standard.

Thank you for all your input,I knew I had it wrong so glad I asked.Thank you again.Will post the pics if I can ever figure out how to shrink them!