Our company still produces neon in-house. But our neon guy is getting up there in the years and isn't far from retirement. It's really depressing how little demand there is for neon in most places anymore. There are some "oasis" spots with lots of new neon signs, like The District next to downtown Nashville. In most places customers just don't want to pay the cost for the neon, its power demands and possible maintenance issues.
As to which fonts are best for neon, I generally use fonts that have a very very thin stroke width, like an "ultra-light" or "hairline" weight. Some sans serif fonts like Interstate or Helvetica Now have those. At full size those hairline letters can be outlined to to the thickness of the neon that will be used, be it 10mm, 12mm or something else. It's also possible to use decorative fonts that have an inline effect on them. Sometimes those can be handy if you're going to have printed graphics on the background and single stroke neon installed on top. I've designed quite a few store interior neon signs with vinyl decorated PVC faces with exposed neon installed on the faces.
Scripts can be a bit more tricky. If the neon isn't going to have a printed background I'll often hand draw a single stroke script and then digitize single stroke vectors over the script sketches. I'll work with our neon guy to make sure each neon unit isn't too short or too long and won't have too many bends, double-backs, joins, etc.