We need to know more about the tank to give you a better answer. What are you going to use for a substrate? What kind of lighting, and how strong? What fish? What's the temperature going to be? Were you planning on doing CO2?
Because a 90 gallon is 24" high, you really need to consider more lighting than just a regular fluorescent lighting. If you can't do this, I would expect only low light plants such as anubias species, crypt species, java moss, and java fern. There are others, but this is what I am most familiar.
Also, to stock a 90 gallon tank with plants, you will spend some money. Some plants cost a lot more than many fish species do. Let us know exactly what you had in mind, and we can give better answers.