I have too little experience with IPE to comment intellegently on it. I have built several wood and trex decks, one with cedar rails. It looks and works well. The clients are happy with it.
Trex does have low maintenance and looks good. Make sure it has enough support. Joists need to be 12 inches apart rather than the
16 or 24 inches you can use for wood. Same with the steps.Also note that you would not want to put anything heavy on the deck. If the planters you spoke of are larger than a couple of gallons, put put a layer of wooden decking under the trex in those spots to avoid sags. Don't expect to put anything on the deck for any length of time of the mass and weight of a piano, freezer, or lawn tractor. You don't usually have to worry about weighing it down with too many people; they don't usually stay long enough to create sags.
Enjoy your new deck.
Peter