There is a ton of versions for coin to sugar packet. I like and preform two versions but they have some flaws. I'm looking for a version with two requirements, their coin is signed, and also they can open the sugar packet and dump it out. I don't care about impromptu or not. I'm just looking for something like that to do in a restaurant environment. What do you guys recommend ? If there is no version like this, then whats your favorite version and why?

Try looking into Diamond Jim Tyler's effect called SWEET. It is a signed coin to sugar packet and from what I remember, it was very practical. Jim typically performs in a restaurant/walk around environment so he needed something practical and easily reset. I believe SWEET should fit the bill.

Diamond Jim Tyler teaches a method in a trick called How Sweet It Is that fits all of the criteria you've mentioned. http://www.penguinmagic.com/p/S11661 Low cost purchase for a high impact trick. I get great responses from it and have restaurant patrons ask me to perform it for their friends.

Thanks I'll look into it because every time I did it impromptu they wanted to be the ones to open it which was problematic.

Spellbinder has a special version for kids (and adults who are just big kids) in The Wizards' Journal #24. Don't get put off by the Halloween theme- that is entirely optional. His effect is described like this: Start by awarding a child an "official" I was Caught Being Good plastic coin. Have the child initial one side of the coin and you initial the other side of the coin (or you can apply Halloween stickers and initial those instead). While you hold the coin in your hand, the child freely chooses a bag of candy from a basket filled with candy bags. As soon as the choice is made, the coin vanishes from your hand. The child tears open the bag and dumps out the candy to discover the coin, still containing both sets of initials, inside the sealed bag of candy. The child gets to keep the candy and the coin as souvenirs.

I purchased Diamond Jim's Penguin lecture where he teaches it and am very happy but was wondering if anyone here knows how to and or do this in a casual situation?

This doesn't meet the 2 requirements that FrankieF noted but Sol Stone and I published a version in Apocalypse Volume 18, number 6 on page 2514 (June 1995).