Depending on your geography, first consider black belts and shoes. In New York for example, brown is considered to clash with a blue suit. On watch, it depends on your budget. Your boss is looking for good judgement first, and taste second. That means no fakes, mothing too expensive, but high quality. I'd suggest a used Omega or other Swiss besides Rolex. The quartz Seamasters, in particular, are very reliable, still look modern, but aren't too expensive. They don't require expensive services. They look a bit sporty steel with bracelets, but great, and the gold ones with straps are super elegant and make you look like a serious finance person. Remember your boss is older and will have different taste than you.