Really, any durable vinyl/plastic type flooring or expanded PVC (although not a flooring product) would work.
I like the expanded PVC simply because it conducts heat. In other words, the transition from warm end to cool end will be a more gradual. I'm sure you know what I meant but someone else has asked me so I thought I should include it.
There are numerous adhesives that would work to hold down the various materials. Regardless of what one uses, it is important that the edges are siliconed completely to insure that moisture does not get underneath.
Another option is to not have a floor at all, at least not a wooden one. I've made a handful of 4'x2'x2' cages that were stacked on top of each other - none of them had floors.
Then I simply attached flimsy 1/8" plastic wallboard to the bottom, making for a more water resistant and cheap floor. This saved a lot of weight and the floor was easy to change if it sustained too much damage.
This is not practical for larger cages where the floor adds structural integrity.
I then made a rolling platform for the bottom cage to sit on and that supported the floor of the bottom cage, making it rigid. The top of the bottom cage then acted as a suport for the next cage and so on.
Regarding sliding vs. flip down doors, that's totally a matter of personal preference. I work with a lot of fast and aggressive species so it is not realistic for me to keep my snakes in cages with flip down doors. I'd never see some of them again.
I like sliding doors because I can open the door just far enough to remove a water bowl, introduce a prey item on forceps, etc.
But for some slower moving species flip down doors give access to the entire cage for cleaning or getting the coils or a large constrictor pulled out the front, etc.
Either way there is a tradeoff. That fact that you said you like flip down doors is all I need to hear - you should use them.
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When attaching the vinyl to the inside of the cage, how do u attach it? I'm just wondering because in my experience moisture would be trapped under it if not sealed totally and cause rotting and nasty things to grow... You are talking about the extruded pvc style sheeting, right? OR the wallpaper sticky stuff?
One other thing... Sliding front, or drop down front? I like drop down fronts, and saw some nice supports for them at Rockler, but have not used it in cage building yet....