These two species have similar care, but they require different cage sizes. I would not keep a pair of giant day geckos in anything smaller than a standard 29 gallon aquarium. A better choice would be a 37 gallon aquarium. Larger terraria will be need for a trio.
The smaller gold-dusts do better in twenty gallon tanks, standards are fine, but a twenty high is the best choice (although hexagonal ten-gallon aquariums are fine for a pair of gold dusts).
In terms of care, both need full-spectrum lighting and bright basking lights with a temperature gradient inside the terrarium of 80-82 °F in the cool end to 89-95 ° F in the warm end. Night temps can be in the mid-to-low seventies to upper sixities. Humidity around 75% is best, but does not have to be exact. I highly recommend a light timer to control the animal's' photoperiod. Substrates of fine-small grade orchid bark or Reptibark work, as will a layer of topsoil/organic potting soil free from perlite, foam rubber over a layer of pea gravel. Live plants such as snake plants are great choices for day geckos, as are other tropical plants. I highly recommend you take a trip to Micheal's and get some bamboo as well: it is helpful when trying to breed these lizards.
Diet: Crickets, waxworms, fruit (fruit babyfood works well), fruit flies and other small insects are readily taken. I used to feed my Phelsumas "meadow plankton" but you must be careful where you collect it. Another trick for collecting food for small lizards: place a porkchop, chicken leg or other meat item on a table in the sun, then get a butterfly net to collect the flys that gather around it a few hours later.
Water and humidty can be provided via spray bottles.