No. It is not supposed to be a desserty beer, nor does it have any connection to cream soda. Save the vanilla for porters and stout, IMO. I made my cream ale a little different by goosing it a little with a late addition of Ahtanum. It's still in primary, but the gravity sample tasted awesome. A half ounce at 5 minutes added nice character that isn't overwhelming.
That being said, it is your beer, so if you are dead set on vanilla, you should probably use vanilla. I would split a bean and soak it in vodka for a day or so, dumping the whole cup or so of vanilla liquor into the bottling bucket. Another way would be to pull a bottle sized sample and use a dropper to add a measured amount of this liquor, find a nice balance, and scale up to 5 gallons. Add 3/4 of that amount to the bottling bucket, and adjust from there. Bottle and enjoy