You will want light cotton/linen clothing because it will be hot, hot, hot. Depending on how rough the hiking is you might want closed-toed hikers or you may do fine with trekking sandals, like tevas. Remember you will want to dress modestly. Take lots of sunscreen and a good insect repellant.

Kathie is mostly right. The one sticking point in your itinerary is Mount Bromo. If you do the whole watch-the-sunrise thing, it is unbelievably cold up there waiting for the sun to appear. You will want a jacket. If you don't want to lug one around with you for the rest of the trip, there are lots of places around the area that will rent them to you.

Agree, you need to be prepared for extremes. For Bromo I'd suggest warm but light fleece plus hat, gloves, scarf, which are easily packable. In Bali I like longsleeves, longpants for hiking because of bugs and sun.

I also agree that you need to pack light clothes because at this time, weather is hot and dry. For hiking light and easy suit is affordable & do not have any negative impact on hiking performance.

Don't forget a hat for the sun. Even with sun screen I find my face dries out if not protected.

Michael and marmot are right - I missed Bromo in your post. I'm always amazed at how cold it can be in the tropics.

Thanks so much for the advice. I am packing my fleece right now!