I can't think of anything good in Detroit, you should come back to LOS ANGELES!!!!!!!!!!

Sissi -

In Detroit you want to avoid downtown.  Not only is there nothing to do but its also inconvenient for clients as not too many people work there.

Your best bet is probably in either Dearborn or near the airport.  I love the new Westin at the Airport - great rooms, great food, great service...but parking might be a pain for your clients.  The Hyatt and Ritz Carlton in Dearborn are both great and not a expensive as their counterparts in other cities.  Hyatt is much bigger and thus more discreet.

Hope that helps.  Sorry if my taste is too upscale, but you seem like an upscale gal.