I think you mean "live" in a major metro area.

Personally, I'm well aware of the different ways to get cash back/dining credits/discounts on restaurants. One you left out is www.valpak.com -- they send coupons in the mail but you can also get the coupons direct from their website.

However, in my experience, there are in fact, not that many that sign up for multiple programs, that I find convenient and/or desirable to patronize. At least that's the case in San Francisco. I've searched for these things habitually over the years -- restos that use opentable.com PLUS idine and/or restaurant.com certs, for example.

Also, quite often even if they participate in multiple programs, they will NOT honor multiple programs for the same dine. For example, a few years back, I used a restaurant.com discount cert at a restaurant that also participated in idine. I got the discount, but did NOT get the idine miles. (On the restaurant.com certs, the T&Cs say: "...cannot be combined....") And at another idine restaurant, I used a valpak.com discount but didn't get idine miles. (Used an idine-registered CC in both these examples.) However, the cash discount was worth far more than the miles would have been in either case.

One example of when I WAS able to double-dip was at the Crocker Galleria in downtown San Francisco. Some of the eating places there participate in a "frequent dining" program (see list of participants here: http://www.shopatgalleria.com/frequent.htm ); eight dines stamped on a card gets you one free (up to $6) lunch. It so happens that two of the participants are also idine places: Leila Mediterranean and Pizzelle Sorrento (same owner).

So I qualified for VIP status buying inexpensive lunches, got idine miles and free lunches to boot (and of course the credit card points/miles).