Just back from a meeting in Manhattan today - not really tropical but the humidity was HIGH and temps in the 80's. I wore a moss green silk sweater set and slim black pants with some lycra so no worries about wrinkles from humidity. Black sandals. IN the real tropics I'd wear light colored slacks with some lycra and sandals. This was great for Japan in the summer. A linen short sleeve skirt suit just dissolved into a wrinkled mess. The skirt kept riding up, the blouse got sweaty at the waist band and the jacket was a nuisance to carry when not in air conditioning. I threw away one suit because it was such a mess after a hot day in Osaka.
I prefer to wear pants rather than skirts with sandals in the summer. I don't like to wear skirts without hose (another thread!!!) and when wearing hose I always need to carry another pair because I'm paranoid about wearing runned hose. (Catholic school girl worries do hang on!). I like pants cause its just one smooth line to sandals.
Another top idea is to find a sports top with wicking material that also will do for business.
I feel cool if my clothes are light and "smooth". I feel hot and sloppy with clothes that look messy, rumpled, need "tending" and this distracts me in a business meeting. Clothes with some lycra allow that sleek cool look and feel, pastels also seem to be cooler. I also prefer pants to skirts for business when getting in and out of limos, planes, trains, carrying briefcase, purse, papers for meeting,etc.