Best commuter style case with a belt clip?

Hey there Apple core, got a quick question and hoping someone with some more experience in the matter could give me some advice. Here at the company I work for, we are upgrading all of our employees to iPhone 4S's within the next few weeks and want to buy cases for all of the phones to ensure that none of them meet a nasty, percussive end.

For those in the business who are out and about constantly we are getting Otterbox Defenders, which I know and love as being awesome cases, and they come with a belt clip which is a necessity for these employees. But for the people who work inside of the office, I want to get something a little less bulky, but still has a belt clip. Unfortunately, the Commuter does not have a belt holster, so that pretty much disqualifies that. I have had a hard time finding any other protective cases that aren't super bulky but have a belt holster.

Does anyone have any advice for me? I'm hoping that there is a product out there which addresses our needs perfectly, and that I'm just missing it because I imagine that there would be a lot of demand for such a product.,

Thanks,

Michael