Actually, Diners Club now (since a couple years ago) is the SAME dining program, just under a different name. Their Restaurant Savings program is simply a no-additional-fee (beyond whatever your annual fee for Diners Club is) version of the cashback iDine/Reward Network program, except that of course it only works with the subset of iDine restaurants that accept the Diners Club card (and for some strange reason, not even nearly all of those).

It was only before a couple years ago, when Diners Club program was instead affiliated with Le Card, that it was completely separate from iDine.

As already mentioned, idine restaurants tend to be way more expensive than the other ones, so the 10mi/$ makes the price more palatable. If they drop that to 3 miles, who needs them?

That isn't always the case. There are some very reasonably priced restaurants in the IDine program - the ones that are more expensive - I tend to stay away from, even with the discount. If the discount brings the prices to be more reasonable that it's the program that gets me there.

Ive seen very reasonably priced restaurants, go there because you like the place not even the 10 miles per is worth it.

Definitely not the case in my area. In fact, I would say that the opposite is true.

It seems that the Diners plan includes all the IDINE places and they credit your bill 20% at those restaurants.. No fee other than the standard one for the card itself.. Some of the places in the Diners book I don't believe take Diners though..

Not only not true, but somewhat meaningless.

There is no such thing as "all the iDine places" (or at least no easy way to tell what they are), because there are slight variations even between FF miles subprograms of iDine.

For one thing, United's (Mileage Plus Dining) has a feature where once you reach a threshold and you get a 25% bonus on every dine you also see "more restaurants available" (than before, not necessarily more than some other subprogram). So are "all the IDINE places" the ones you see when you're a new Mileage Plus Dining member, or the ones you see when you've reached that threshold, or what?

Second, there are definitely SOME restaurants here and there that participate in one airline's iDine subprogram but not in another's. For example, there one within walking distance of my house which is in Northwest (Wolrd Perks Dining) but not in American (AAdvantage Dining). Is that restaurants part of "all the iDine places" or not?

Finally, forgetting about the definition of "all the iDine places", Diners (Restraurants Saings Program) definitely does NOT list all of them.

I just did a search on CA, Palm Springs & Desert Area, Palm Springs/Cathedral City, and American shows 19 restaurants but DIners only shows 15. And that's in an upperclass tourist area, so Diners acceptance is understandably high.

For a more dramatic effect, look at Maine (which doesn't even have "neighborhood" breakdowns): American shows 51 iDine restaurants, Diners only shows 8!!!

But you are right on one thing:

It works both ways. Some of the places that are missing from the Diners program (but show up in others) DO take Diners, and yes, I see at least one restaurant near me that doesn't even take Amex (and certainly not Diners) yet which is listed in the Diners program. Go figure...