I know I've seen this discussed before but I just can't seem to get search to find the right thread(s). Please feel free to point me in the right direction (or offer some suggestions).

I'd like to give a tip to a couple of hotel club/concierge attendents. A general search seems to point to cash being the way to go and I want to see if that still seems appropriate (especially for the holidays). Other thoughts? Like gift cards (anything specific)? I'm in DC. The club room already has Starbucks coffee, so that doesn't seem right.

Thanks.