Fukien tea is another good choice if you are willing to put a little more work and research into it. They are a great species for bonsai and are very nice looking trees/shrubs.
In general, almost any tropical species of tree can be grown indoors and do well if given proper care. This can require extra work though to keep the environment tropical tree-friendly, but as long as you are willing to invest the time (and possibly some extra money) it should be fine. One of the biggest things to consider when buying a tropical for growing indoors is the amount of light that it will require. Its important to research specific species on your own because plant tags that come with them often leave a lot to be desired, and tropical species vary greatly in their needs. Some require full sun, as they naturally grow in open areas in the tropics, where other may never naturally get direct sunlight because they grow under the canopy of larger trees, or what have you. If the plant requires lower levels of light, or indirect sunlight, most people are able to accomodate this relatively easily. However for those species that require full sun, it's often necessary to work out some extra lighting, unless you are lucky enough to have a garden window sort of thing. Grow lights (ones that produce full spectrum UV rays) can be used for this. They are quite a bit more expensive to buy though, plus the added electricity of running them atleast 6 hours a day, and any setup you have to get, depending on how you decide to do it.
Humidity is of course another factor, but for most species misting and a humidity tray will suffice. Soil is also important. Many tropical species can handle (and sometimes do better with) a greater ratio of organic material, and often higher levels fertilizer like they would have in nature. If you decide to stick to a more common composition of 75:25 inorganic to organic, then you will likely have to water much more frequently, and probably fertilize more often too.
Edited to add: Banyans are ficus (indian tropical figs to be more specific). If given the proper care, they are a perfectly suitable species for bonsai, and in many cases are actually incredibly interesting specimens due to the large number of aerial roots then eventually turn into trunks.