Are the 360 ports of CAVE shooters ok? I only ever bought Deathsmiles so I don't have much of a frame of reference. I also haven't had much luck sourcing any CAVE boards that don't cost a thousand dollars :c
You're fine as long as your screen doesn't lag, all ports are good.
We had an arcade shop in my town, which sadly closed last year to focus on other activities. As far as cabs go, the owner's brother imported Astro City cabs and they had quite a lot of them. Two of them had Super Turbo on versus constantly
because of thanks to us (our fighting games association was a partner), puzzles games were usually Puyo Puyo Tsuu, Magical Drop or Puzzle Bobble.
The owner was a big shmup fan so he had a lot of stuff rotating on his cabs, though he dedicated one of them to Mushihimesama Futari because he loved that game. Besides Touhou and CAVE, look around Psikyo shmups, like Dragon Blaze or Strikers 1945. I could suggest Toaplan but, uh... I'm not cruel.
For fighting games, either Super Turbo or 3.3 would be popular, though exotic choices like Samurai Showdown or Marvel vs Capcom can be nice.
Metal Slug is always a lot of fun on a cab, so I think it's safe to go for it.
If I could choose my lineup on 3-4 cabs, they would be Super Turbo, Mushihimesama, Ketsui and Puyo Puyo Tsuu.