just a note on what seems to work and what doesn't - take it for what it is, but having done a number of these, i feel qualified to lend my advice and observations
coffee meets - works if it's early enough on saturday, and ends early enough - ones that start late or go late don't seem to work well, as most people do not want to give up a whole day - sunday doesn't seem to work well at all
lunch meets - don't seem to work well at all - agreeing on a restaurant, time, location, making arrangements, getting confirmations, et all, seems to be too logistically complicated - also things seem to "come up" at the last minute and people drop out, and somebody always ends up holding the bag
dinner meets - forget about it
after work pub meets - they work, especially in more urban areas, but can be a handful to plan, as many are afraid of driving after drinking
the biggest single factor in making a gathering work is to have an "event" associated with it - a well planned fun run, a wine tasting, a barbeque, a track day, a car show, a tech day, a detail day, whatever, but a bigger reason than just a few guys getting together over a slice of pizza - something that makes it an "attraction" and not just a "wing it" kind of thing
hope this helps - again, take it for what it's worth
let me know if there's anything else i can do to help