I normally use OYL-021 with my Hefeweizens, but according to Omega's website it should be similar to 034. I do not remember 034, so it may be somewhat new. Their description mentions vanilla, while the description for 021 does not. It seems like the comments below are valid for both, but I only have experience with the 021.
I try to minimize the banana by fermenting at 62 F. Fermenting near the high of the recommended range 64-75 F should get you the esters you are after. Also, the first attempt at this style, I made a big starter, and the beer was bland, not at all what you desire. Since that fail, I use a fresh pack for each batch, and don't use a starter at all, and have been pleased with the results. It is easy to overpitch with this style.
I have also used Safale WB-06 for this style, again fermenting at 62 F, and got a good deal more banana with that one.
As a side note, I always do a decoction for this style, and feel it makes a positive difference in my process. This is somewhat controversial, with many others saying it makes no difference.
Hope this helps, and good luck with your Hefeweizen!