Making officers and above the only ones with guild bank access is the safest way to go. If someone says they need something they can ask an officer and they can use their judgement (i.e. a cloth wearer asking for a plate piece or something similar where they really don't need it).
You can also implement 'buying' stuff from the guild bank with officers only having access. Say I have a tailor who makes a bunch of Frostweave bags. Well on the Auction house on Grizzly Hills they're going for 45 gold or so. The guild I was in a while ago charged members 30 gold or so (enough for the materials). Once the member deposited the gold (or even materials to make a new one) the officer they asked would give them the bag. Simple, safe, effective.
I've seen guilds have people join and without the restrictions in place, the bank gets emptied and that person leaves.
Even if you don't have a malicious player raid the bank, if everyone has access and someone's account is hacked you would stand to lose a great deal from the bank if not everything. (Though this can happen if an officer gets hacked anyways. Keep your account info safe!)
The primary reason I asked about how serious you are about this is because my monthly income is quite limited, especially after I factor in buying food and drinks. I've had to start paying back my college loan at the start of this year too. (Meaning I'm usually broke and waiting for the 1st of the next month to get paid.) So you can tell it'd be something of an investment to even move one of my primary characters. (And such a pain to get a new one to where my main is.)
Otherwise if you have any questions about WoW you can either post them here and I'll keep checking in to answer them or if you see me in game or on Teamspeak feel free to ask. I know of more than a few decent ways to earn gold and whatnot in WoW. (Dad keeps bugging me with questions from time to time as well, lol).
EDIT: If anyone wants to make a World of Warcraft signature like mine, go to
http://www.dkpsigs.com/index.php register/make an account (it's completely safe and free), input the character's name and realm/server, select a picture if you've got one (I just screen capped mine and resized a little in paint), choose what stuff on the right side to show and what background and colors it'll all be. Tell it to generate a sig, wait a few, then copy the html <img></img> stuff into your signature and you're good.
