I've seen a lot of names of places thrown out here, but no real explanation why they are any good, so I'll do this:
Lyons Classic Pinball in Colorado is what I would consider the pinnacle format of on-location play. It's the only place I've been that feels like someone's personal collection in their own home, games that are tuned incessantly, rubbed with a diaper, and decorated around. I can come up with 6 main criteria:
1. Game selection
All eras of games are represented at Lyons, the latest DMD, along with SS and EM, all great players and a sprinkling of rare and unique titles with just the right amount of churn. Those that play at Lyons often (leagues, tournaments) are better all-around players than most, which has advantages in certain tourneys. It's no small collection either, listing 37 games.
2. Can you hear the games?
A good chunk of the pinball experience is missing if you can't hear the callouts. Acoustics are important, and Lyons has at most 10 games per room, with carpet and lots of sound dampening decorations which helps isolate noise. Game sounds are like you are playing at home.
3. Can you see the playfield?
It sucks when overhead lights reflect off the glass, blocking certain parts of the playfield. Lyons uses all indirect lighting.
4. Condition, condition, condition.
If a pinball machine isn't tuned up, it is not fun. Games at Lyons are always in top notch shape, even setup a little extra difficult, and taken care of like they are in the personal collection of a type-A personality... which they are.
Many on location places are a big noisy room with bright lights and kids running around with handfuls of tickets and pizza hands. Lyons pinball feels like someone's basement, decorated with personal touches everywhere, GOT poster next to GOT LE, framed classic Playboy magazine above the Playboy game, 8x10 info and history sheet for many games, KISS throw next to the KISS machine, flashing stop light, etc. Background music is all classic rock played on real vinyl with era-appropriate speakers. It is the ultimate game cave.
6. Location / Food / Drink
Lyons itself just has snacks but steps away is a world class restaurant and brewery. It's nestled in the mountains with clear stars at night, next to a park with weekly events. That separation of food and games improves the pinball experience quite a bit, also making it more family friendly than any Barcade. This environment does more to promote pinball to the youngest generation than any Barcade could... I've seen my share of pre-teens eliminating top 100 players on a regular basis here.
Lyons not only meets each of the criteria, it excels at every one of them.