I just think of Biscuiteer as a 35g Wealth. It's a half health, half mana potion. It's okay on anyone that uses mana, a slight edge in pre-first back laning, nothing more.
Picking up Unyielding + Block on supports isn't worth the loss of Nimble if you ask me. Maybe on the melee supports who can't make much out of Pickpocket, since that's the biggest reason for going so deep in Utility, but CDR and movespeed are still pretty awesome on supports (and everyone else). In that case it's not even particularly worth going past Greed though, which gives you five more points to put into Defense where Juggernaut into Defender is a really strong way to spend four mastery points plus a floater for Good Hands, Summoner's Wrath, or 1/2 Wealth.
I like 1/2 Wealth anyway since I always rush Sightstone. It's worth 8gp10+, rushing Philo is for chumps, and you don't need more than two starting wards unless you're warding a buff pre-minions. Most starts benefit from both points but I like Flask + Green/Pink, which leaves me an odd amount of gold where I get a second potion from 1/2 Wealth but not a third from 2/2. That'll get me through to the point I can back for Sightstone and greenies just clog up an item slot after that. Pinks are still useful. Flask > Bead/Charm because it's more efficient and Flask > Bead+Charm (or Flask with one) because you can't get enough extra wards and potions to go with both.
Flask is awesome but your options as a nonsupport are pretty limited starting with one. All you get is Bead/Charm, if you want a future item built from them, or a gajillion potions/wards. Flask+Cloth or Flask+Machete with 2/2 Wealth are cool but ultimately kinda gimmicky since starting potions are so helpful, even with the Flask. You can still pick Flask up on your first back and get a lot of use out of it, though. And unlike potions, which you may not "need" to use and ultimately waste, there's no penalty to just spamming this thing every time you have health and mana missing. Even manaless champions only need to use it six times to get their money's worth but Flask sure makes having a mana bar that much more awesome now.