Physic Desk or Virtual Desk
I don't think I'd ever cut it as an archivist or squirreled away in some musty storage library. I enjoy my human interaction so maybe that's why I'm not too fond of AskNow. I enjoyed chatting with Meebo since I do IMs and the librarian seemed to have more time for me. They let me know I would have a wait, and I really appreciated that they didn't leave me hanging like AskNow did to me. Really, they should have something in the chat window that says something like connecting or locating a free librarian. Some people might enjoy efficient transactions, but I've noticed that a lot of people take a while to get around to what they really need. When a kid asks for science experiments, they're either focused on getting any doable experiment or they've got a particular branch in mind but don't know how to ask. I'm not sure that some of the people on virtual reference would be able to guess. I have to pester some kids when I see the disappointed look their faces when I drag them over to the shelf. Sometimes it's not enough information and sometimes they've got several homework questions.
Chat reference is maybe a little more casual. Teens would probably like it better than an actual library since most teens are pretty hesitant about even approaching. Most teens also use IMs anyways so they'd potentially get some questions answered while chatting up their friends. So I have friends asking me reference questions every now and then but I'm generally talking with a few people while I'm looking.
I like the idea of virtual reference, but if I had to choose between staffing an actual desk and a virtual desk, I'd have to choose the actual desk. Virtual reference is great, but with all the other nifty tools we've picked up this semester, some libraries overdo things and spread their staff too thin. It's a really odd situation techie librarians face!
