Opinions...

My girlfriend is nagging me about making a "banana beer" so I formulated one based off of a Hefeweizen in hopes of getting that banana/bubblegum effect using WLP300 (Hefeweizen Ale yeast). But to accentuate it, at the very end of the boil I'm going to use either fresh or dried bananas to really bring it out. Other than that, typical Hefeweizen using about .5 oz. Saaz hops for aroma and 1 oz. of Hallertau for bittering. Any opinions?

I've heard of bananas being put in the fermenter or keg for hefeweizens, but, in my opinion, it's unnecessary. The yeast should give you the banana/clove/bubble gum flavors on it's own. I would worry that adding banana may be TOO much for the beer or getting a weird off flavor from the boiled banana.

Of course, it's your beer, and you can do whatever you'd like. Experimentation is one of the fun parts of homebrewing.

yea that seems to be the general concensus. I'm just going to use a little bit and see how it turns out. maybe i'll throw some bubblegum in there too...haha just kidding.

Bring the fermentation temp up to 74-76 and you will get a natural banana off-flavor. Some people hate it but in my first few brews this happened unintentionally and my friends loved it and actually ask me to brew a batch like that intentionally now from time to time.