You're looking at 2 chameleons that get big but have very different environmental needs.
Veiled---desert conditions
Panther---Rainforest conditions
Height is more important than width with either type. Go with a cage that has at least 4 feet of height. 30" square is fine otherwise.
The cages I have are homemade and built out of 2x2's and nylon screening with a door built into the front.
I used dried branches for infrastructure and silk plants I picked up at a craft store that came in 6 foot ltenghts. I strung them throughout the enclosure to provide cover for the animal.
Use a basking lamp and have a branch underneath that will provide the animal an opportunity to be anywhere from 8" to 15" away from the lamp. They will look for high heat first thing in the day and may travel back and forth otherwise. They will seek out heat in order to digest a meal.
Never ever have loose feed animals like crickets in the chameleon's enclosure. They will hide and at nighttime will crawl all over the enclosure, including on the animal. This can be very stressful for the chameleon and the crickets can actually try to feed on the moist parts of the chameleon, namely its eyelids and it's anus.
For crickets, I used a deep plastic yogurt container that I pinched between two branches. For worms, depending on the size of the chameleon, I might use a more shallow dish. The chameleons seemed to prefer the container suspended about halfway up in the enclosure. For a young chameleon, dust everything you feed with calcium powder. For adult animals, dust with calcium twice per week or so.
Drinking water can be provided via drip bottle or by simply misting the leaves once or twice a day. Soem chameleons hate drip bottles and they can be messy if you're not around to monitor the flow. Misting heavily on one or two leaves will provide enough.
I would use a full mesh enclosure with a veiled and only mist the enclosure once a day for drinking water.
I would use a partially meshed unit with a panther and either mist twice/three times a day or use a fogger with the water protected by screen/mesh to avoid the animal crapping in the water.
Be prepared to pick their feces out of the cage every other day. They can really stink up a room.
I would only keep single specimens from both of these species. Only Jackson Chameleons should be housed in a community set up.
Even if your plan is to eventually breed them, they should not even see each other. The female will get so stressed out if she can't avoid the male's gaze.
Hope that helps.