I've built an admin interface recently, but I didn't ask for input. Frankly I should have, but I think it's fair to consider the use of administration interface the same as standard user interface. It's just got more navigation paths and configuration options.
Having said that, following is a list of things that I'd consider mandatory if I were launching a survey on any new admin interface:
UI shortcuts to most-frequent tasks: (info applicable to the entire collection of admin users)
- In advance, what do you think your most-common management task may be? (Text or list of 3-10 options that you come up with for the survey)
- Do you have experience with other admin interfaces? (Y/N) followed by "Can you tell us what you like most about them, and what general admin tasks you do most frequently with them?" (Text)
Front-page stream of updates (info about an individual admin's personal preference):
- Which style of streaming updates do you prefer, Facebook's conversation-style or Twitter's compressed format? (radio buttons)
- Regarding notifications of important system events (like new users, problem reports, etc) do you prefer every notification delivered immediately, or to your account inbox, or __ (fill in the blank for the admin system specific message delivery abilities) (series of checkboxes or radio buttons)
Extras, not so manditory:
- Do you prefer the design scheme (colour/layout/etc) as similar or very different to a standard user sign-in?
You could also consider an event-based survey... Clearly inform the new client about a "Survey mode" currently active on the site while they're logged in, to watch their use and give applicable questions when they enter particular areas. You could permit them to opt-out, or choose to force them to give feedback, depending on how critical this survey is to you.
Hope that helps!