staff were fully paid (not $2 per hour plus tips) for their services prior to the event. She said yes and know tipping was required/expected. So I tipped $50 to each worker on top of their normal pay and $100 to the bartender that I had a mad crush on. Afterwards, I was told that the bartender put out a tip jar and that this is an etiquette faux pas unless it is a cash bar. If it a free bar, tipping should be required of the host and not the guests. I still do not know if my tip level was considered appropriate (whatever that means).