when i was in the corporate world, i either wore a dress, skirt/top combo or a tuxedo pant/top combo. for me it depended on the location b/c i didn't want to overdress for a night of karaoke & appetizers, but didn't want to underdress if we went to a hotel banquet room.
it also depends on how large the company is. if it's small, you don't want to look too done up. one year, we opted to go to dinner & a play & the next we did a large banquet @ a semi-casual restuarant.
i'd wear a black dress w/a pair of chandelier earrings. or, tux pants & an eye-catching top.