I can't think of anything that I would do differently. I have had 3 distinct iterations of my cab, and I really feel that I needed all of them to find out what I really wanted.
I started with X arcade controls, and then switched to Happ stuff. The Happ stuff was better, but I instantly realized that the cheapness of the x arcade stuff wasn't my issue. My issue was that I was trying to use a fighter stick for classic games. Once I figured out that controls were really (ridiculously, even) important to me, I went modular, and I was happy. I was still trying to get a real arcade experience by using a cabinet and arcade monitor, and it became frustrating over time. There are just too many differences in 20 years of games to get them to all play correctly on a low res monitor.
When I gave up on that idea, I decided that simulating would work better, so the arcade cabinet was out, and a showcase cabinet with a big flat screen TV replaced it. this seems to still be good for me. I rarely use it though. lol
That has been the one constant over the almost 13 year history of this project. It has always been more of a design challenge than something I use daily. I started buying dedicated machines in 2005, and I spend most of my arcade time in the arcade. I have had well over 100 games over the years (currently at 12, which is a nice, manageable amount unlike the 22 I tried to cram in the garage once), and it has changed my opinion of the MAME cabinet over time. I think of them as separate. My MAME cab has never been in the arcade, and it never will. It is a different experience, and I like that. It is a test machine that also allows me to play any game I want. Having that ability has changed the way I think of my old favorite games as well. I built this so I could use any of the specialty controllers, since those were the games I remembered liking. It turns out that those games are really only fun in short bursts. The driving games, shooting games, the yoke games, etc are fun for a while. Most of the fun is in the interface though, and the games just don't seem to have as much replayability. I find that my MAME choices, and my dedicated cabinet choices are gravitating back towards joystick games. I would now like to add a Mr Do to my arcade (if I can ever find one), and I just bought a frogger. I can play both of these fine on the MAME cab, and I even have the joystick for Mr Do. I would like to play them in the arcade though.
I have always heard people say that you just can't replicate playing on a real cabinet, and I guess I am starting to see that a little. It took 13 years though.
I guess what I am trying to say is just try what you want, and then build on that. It is the missteps in this hobby that make it fun. When I tried to play Donkey Kong on my first cabinet with a fighter joystick, I had no idea what was wrong. I just knew that a game I hadn't played in close to 20 years just felt wrong. That moment was the start of hobby that has kept me entertained for over a decade. It led me to own a real Donkey Kong, and a lot of other games. The hobby forced me to learn a little about electronics, which made me want to learn more, which led me to a career as a computer engineer. That chain of events only happened because I tried stuff, and then with that knowledge, tried some other stuff. In early 2003, I had no idea anyone but the Silver Spoons kid actually had arcade games in there house. Now I have an arcade in my garage that includes everything from my earliest favorite game, Stunt Cycle, to what I think is the best pinball machine ever, Metallica.
Don't try to shortcut the learning process on this hobby, because at the end of the day, that is what makes it worthwhile.