Over the years, I have taken vitamins on and off. While they never hurt me, I can't say they did anything for me either.
Only two times did I had a noticeable effect from vitamins...regular dosing of ZMA, B-complex and Chromium. I think it was mostly the Chromium, but I was always hot and felt amped up (more unsettling than useful). The other time was Glucosamine/Chondroiton. I had a creaky knee and after a month of G/C, it went away. However, that's the same time as any natural minor body repair would take, so it could be coincidental.
This doesn't mean that they don't work, but I think effects are minimal if you are eating a range of foods with decent nutritional value. When was the last time you had any significant quantity of oranges...if it was a while and you don't have scurvy, you get my drift.
That said, I am finishing off what vitamins I have left over during my current routine. It should take 45-60 total days to use them up. After that, I don't plan to take anything other than vitamin C as needed.
I do like the gummy vitamins, but that's more because they are like gummy bears than vitamins.
Also, dark beer, chocolate and bacon have vitamins!
Current vitamins I am taking daily until they run out:
Vitamin B (2)
Vitamin C (2)
Vitamin E (2)
Fish Oil (1 sp) I keep forgetting the fish oil!