I think the number of visits varies widely from venue-to-venue; price is definitely a big factor (easier to become a regular going 2-3 times per year at a fine dining venue than at a neighborhood bistro); size of the restaurant is another factor. For me being a regular has more to do with being recognized by some of the staff when returning and developing a friendly rapport with the staff than perks - though perks are certainly appreciated. Some restaurants we felt as thought we were regulars after just three visits whereas others we have frequented over ten times and it is still the same vibe as our first visit. How profitable a restaurant is also can make a huge difference in how many perks they are able to pass on to regulars (the venue where we received the most perk was part of a luxury hotel and therefore had far more disposal income than a neighborhood bistro). The restaurant's philosophy comes into play as well; some venues strive to treat everybody the same; at the other end of the spectrum are extremely cliquey venues with most lying somewhere in between.
My wife and I eat out quite a lot and do a mixture of trying new venues as well as fairly frequent visits to a handful of favorite venues. What we receive from places we are regulars varies quite a bit across the venue (and even across visits within the same place) but the following would be the most common perks:
*Being assigned a prime table - i.e. view of the kitchen, a four top when it is just the two of us etc.
*Access to tables held back for regulars/VIPs when no reservations are otherwise available
*Ability to have seats at the bar reserved for us
*Delivery of an extra course or dessert to the table
*Complimentary glass of champagne upon arrival, round of drinks comped, a course comped or a percentage of the bill comped
*Having something prepared off menu that the chef knows we enjoy
*Being delivered a food or beverage not yet on the menu and asked for feedback
*Visits from the Chef and/or GM
*Invitations to special events at the restaurant
*And of course some visits we receive nothing at all and that is fine; IMHO extras should be appreciated but not expected
In terms of what the restaurant receives:
*Our money
*Customers who are fairly easy to please, treat the staff well and tip well
*Advertisement in terms of us recommending venues we love to friends and via social media
*We do occasionally give gifts to people at restaurants we have become friendly with - though not too frequently. Examples would include my wife baking something to give to the staff to adjunct their staff meal, a bottle of sparkling wine to the chef as congratulations if they recently received some award, some booze to a GM as an engagement gift etc.
Twitter: @Goof_2