Thanks for the helpful replies, even if they don't totally resolve the issue.

FWIW, at least informally my wife's organization (a large professional association) doesn't care at all about spouses tagging along. You often see spouses in the hotels for conventions and the like, and she's introduced me to the CEO and other top executives if we've crossed paths. But she has understandable concerns about converting that informal understanding into a formal submission of a receipt that includes my name. It could be that there would not be a problem, but she doesn't want to push it. Sometimes informal arrangements last only as long as no one seeks to formalize them.

She's also included my name beforehand or at registration a few times at other hotel chains, with our getting the resulting perks due to my higher status. But that's been when her room charge has been paid beforehand by her organization (so there is no receipt to submit), and I pick up the bill for any additional charges during our stay, such as room service.

Anyway, the situation seems different where she will be getting a bill that she'll need for reimbursement for and where I would want to try to get the DSU benefit confirmed beforehand. Hence my question to begin with, finding out whether anyone has had any specific experience with this situation. My guess is that it may come down to the specific hotel, but I'd still welcome any ideas and examples of specific experience using a DSU under these circumstances.