Hey I have a 12ft. alumnium jon boat and I'm debating whether I should add a casting deck and marine carpeting. Not really sure if it's worth it or not and I'm just wondering what some of you think?

do you stand and fish off the seats already?  if so, add a deck so you have more room

How wide is your boat? I have a 1436 that is so unstable I would not even think of decking it. However, my 1448 has front and rear decks, it's amazing how much difference the added width makes.

A 12' boat is less than ideal to say the least.  But it can be done.  I had one, a 1232.  I fished out of it for years and loved it, but I wouldn't have put a deck in.  I just carpeted the floor and stood on the carpet.  Not great for 2 people, but fine for one.  I caught many fish from that little boat.

I decked out my 14' jon boat and it worked fine and very stable.

If you put a deck on that 12 footer , you are indeed a brave man.

Deck it man. There's an article from this very site that talks about this issue. Read it, it doesn't disappoint.

Here it is http://bassresource.com/fishing/bass_boat.html

HERE is a suggestion

I just want to add that I fish 2 people in this boat almost all the time.  If you fish alone, deck the front.  If not, I highly suggest this set-up.  I've had every possible set-up for a 12 ft jon that there is.

This boat fishes 2 people very well because the guy in the back steers but the guy in the front,...still has the front.  Very fair.

But again,...if you always fish alone, deck the front, use a bow mount motor and run long leads to the batt's which should be in the stern for weight displacement.  Otherwise, I highly recommend the set-up in the link above.