Re: UV lighting and darts-- This is unnecessary and difficult to use with dart frogs. They will avoid it, not bask under it. In a rain forest, the UV that reaches a forest floor is very filtered and scattered by the canopy. The food items are dusted with vitamins, calcium plus D3, the D3 being the necessary ingredient that is otherwise provided by UV in unfiltered sunlight. However, since most of us enclose our tanks with a glass lid which filters out all UV light and the high humidity and misting and heat control precludes using bare lights within the tanks themselves, few dart keepers utilize UV lighting for darts. There are some acrylics that do allow UV penetration, and you may find other plastics that are rated for this. But glass does not. The UV range is invisible, so it does not add to the tank color. The visible light from UV bulbs is from the incidental visible spectrum of the bulbs. Plants do not utilize the UV spectrum. Therefore, the tank lighting is mostly for the sake of the living plants, which use a mid range of around 6700 Kelvin to best all around advantage.
The advantage of natural plants is that they help recycle wastes biologically, increase humidity, and along with the natural organic substrates and water features, help modify temperatures.
There are hundreds of suitable tropical plants for vivariums. I would recommend staying with the smaller species, including small-leaved vines. The most popular bromeliads are the Neoregelias, as mentioned, which can be colorful with suitable lighting, hold water in the leaf axils and can be grown epiphytically on branches or backgrounds without growing extremely large or needing much nourishment except for the detritus that accumulates in the leaf axils and what the aerial roots can glean from the humid air. They will grow quite well wired to branches or pegged into backgrounds such as cork bark. Almost all darts will use the bromeliad axils as resting places or hides, and the thumbnails and obligate egg feeders like pumilios will raise their tadpoles in the water filled central vase and leaf axils.
Here's a photo of some of my juvenile galactonotus huddled down in bromeliad axils. Some old adults are now using the brome leaves to deposit eggs.

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Patty
Pahsimeroi, Idaho
D. auratus blue, auratus Ancon Hill, galactonotus orange, galactonotus yellow, fantasticus, reticulatus, imitator, castaneoticus, azureus, pumilio Bastimentos. P. lugubris, vittatus, terribilis mint green, terribilis orange.