I recently bought Janna, and looked up a guide. It had lots of aura items, but none that would make me really table tipping. I wanted a bigger shield for my teammates, more damage, more healing. I believe I have made a guide fitting those criteria.

Utility

40% Cooldown Reduction
20% Spell Vamp
380 Movement Speed

Attack

397 Ability Power
102 Attack Damage
.902 Attack Speed
0% Critical Strike Chance

Defense

2564 Health
112 Armor
30 Magic Resistance

Pick One

Heal Heal is a high sustain summoner spell that will help keep you and your carry in lane as long as possible, however, it has a longer cooldown than most spells, such as Clairvoyance.

Clairvoyance Clairvoyance is a good summoner spell for checking bushes while avoiding the commonly fatal facecheck, and also has a short cooldown. All these components make it a great choice for a summoner spell.

Clarity Clarity is not a recommended spell. If you end up getting stuck soloing bot because of your carry getting low on mana, this may or may not be a good decision.

Pick One

Flash I find flash optimal because of the ability to juke your enemies through walls, or catching up to make the kill. It has a fairly long cooldown, but in the end, it is worth the wait.

Ghost If you prefer to get back to lane just a little faster before you get your boots. Not as good as flash for escapes, as you can't go through walls using Ghost.

Teleport Has minimal escape powers, but gets you back to lane to save that turret. Not recommended.