I have made a number of Cream Ales but will admit I have not tired adding vanilla yet, in fact I have a Cream Ale fermenting right now. I will say from my judging experience that I see a lot of beers like porters and stouts adding vanilla and most of them miss the mark. Of the 100 or so beers I have judged with vanilla, I'd say 80% have either very little or no detectable vanilla flavor. I have been told in discussions with fellow judges on this that vanilla beans are hit and miss and unless you can find a reliable source, it's kind of like pot luck. This made me start to ponder whether I should start with an extract when I do go to make one. Perhaps others on here have better experiences, but that's at least what I can tell you from having judged beers with vanilla in them.
Keep in mind that you are making a Cream Ale, which is much lighter than a porter or stout so those beans, if you choose to use them, will not be competing with other strong flavors like roasted malt or chocolate.