I also tried to brew a Hefeweizen, using all the tricks, like what I drank while was stationed in Germany. I finally figured it out, took some to my old drinking buddy from Germany and he said "Now THAT's the taste I've been missing."
The two things that got me there are Lallemand Munich Classic dry yeast and open fermentation. I had found a post on here, and I can't find it again, about open fermentation and using a storage container as an open fermenter. The thought being that the shallower the fermenting beer the less aroma that is released with the CO2, where with a deeper fermenter more aroma was released with the turbulence of the CO2 coming from the bottom of the fermenter. When you smell the banana from the fermenter, that is aroma that that will not be in your final beer. Am I making sense?
Anyway, I use a 15 gallon sterilite container from Walmart and a blichman cooling coil for temp control with my gerry rigged "glycol" chiller.
My recipe:
55% Wheat
40% Pils
5% Carapils
Mash @152F
Boil 60 minutes with 1 oz tettnang or hallertau per 5 gallons
Ferment @68F with one pack Lallemand Munich Classic dry yeast
I package at around 10 days, after the krausen falls.
Bottle to 3 volume CO2. When you pour ensure you stir up the yeast and get it into the beer, there's a lot of flavor in it. That's how the Germans drink it.
Don't keg it, the yeast will settle and it will turn into a Krystalweizen. You want the yeast in the beer.