There's a reason we use vision cages in all of our stores!
They are extremely easy to heat, clean, and use for years - the one and only problem we've ever seen with them is that they can become stained from bedding after a long time, or if they are not cleaned as often as they should be.
If I may offer suggestions for getting the most out of yours for the long term:
When stacking them, provide some sort of support or brace so that they do not lean or slide. The bottom cage of the stack often gets every so slightly warped so that the glass cannot be easily removed; this is why I suggest a shelving or brace system.
Using vinegar and water will get water spots off the glass. Simple green works like a dream to get poop and bedding stains up; I suggest completely cleaning out all substrate and wiping it down at least twice a year (if not more often).
Watch any lights you use; if the heat light falls and slips off the metal grating, it can and will melt the plastic. Do not use UTHs on any cages sitting on the floor, ESPECIALLY on carpet.
Hatchling ball pythons can fit between the glass pieces; a bit of weather sealing foam in the middle (and the sides) will keep them from squeezing out.
For 221s, you should be fine using 10 - 20 gallon size UTHs. I prefer to light mine with ExoTerra compact tops, and I use the Ion bulbs as they're nice and color balanced, and BRIGHT. Makes the cages look nice, and the compact tops are cheaper (as well as the bulbs) that the tube fixtures, plus they fit a bit better and will not fall out.
If you have any other questions, let me know!
-Jen