A lot of the fun of keeping a captive bred tarantula, or a wild tarantula, again, is understanding where it comes from, and in your mind's eye thinking what that area of the world looks like. If it's a Costa Rican rain forest, you might want to do something with a lot of draping plants, some leaf litter at the bottom, a lot of mosses, and a lot of humidity loving types of plants. Live plants are fine when you get into this environment, tarantulas don't eat plants. Certain lizards and things could eat plants that might be toxic, but tarantulas are not herbivores, they're not going to bite the plant. So just about any plants that you find in the terrarium world would do.
I tend to prefer plastic plants just because it keeps, it's easier to maintain them, you certainly don't have to keep them alive, they're already plastic, and some of them are very naturalistic looking. This one here emulates an orchid with a piece of bark, moss, the leaves, and the orchid, and once that's set up and out of the box, it looks just like the real orchid, it looks like the real thing, very, very natural. You take it out if the tarantula messes on it, it's a simple thing to take and wash in the sink. A variety of others have suction cups on them, and you can hang them from the top of the tank, let them droop down, and give the illusion of vines coming down, very, very cool looking plants, and there must be 50 or 60 different brands on the market today.
This is the best part about building your own terrarium. Some people like to just go to the store and buy as is, many people in the hobby, though, want to put their own together, and that's the fun part, is to shop in a store that has all those products, with different types of cork, this one could be used as a hide and a decoration, pieces of flat cork you can actually glue to the side of the tank, beautiful wood from the southeast United States, this company put it on a rock base so it can stand and the substrate can go over it, what a great decoration for a desert tank, and a tarantula can crawl all over it, and on and on it goes. so there's the beauty of it.
You can, I guess, over decorate a tank if the tarantula can't move around, but for the most part, I sometimes get the book and look at the area where the tarantula comes from, and copy that picture the best I can with the products I can get my hands on. Decorations are what makes it work for you. The tarantula doesn't care too much what brand you use, or what plant it looks like, but if you want to be a purist, you get a plant that comes from the area it comes from in the world, and that makes is really look a lot more naturalistic. So plants are good, live plants are no problem for a tarantula, and that's the fun part about building a terrarium.