Would be nice to see on each port instead of the blue solid background color.. a custom still-live screen of the port; similar to Age of Empires III home city and how it is still but also live and some wind movement / people movement.
Each island can have a different set of appearance in the port background screen; but each port based on its own development and size can show how whether it is packed with buildings or a minor port with few buildings showing in the back.. and on this port screen players can trade, use all the current port interface.
http://www.ageofempires.co.nz/images/aoe3/screenshots/French_World_Trade.jpg
http://vignette2.wikia.nocookie.net/ageofempires/images/7/74/AoE3SevilleTurquoise.jpg/revision/latest?cb=20101016115922
http://vignette2.wikia.nocookie.net/ageofempires/images/b/b2/Londonevening.jpg/revision/latest?cb=20071109140324
http://vignette2.wikia.nocookie.net/ageofempires/images/b/b2/Londonevening.jpg/revision/latest?cb=20071109140324
http://pcmedia.gamespy.com/pc/image/article/645/645630/age-of-empires-iii-20050825052652310-000.jpg