American Express Membership Rewards - Am I too late to take advantage?

I have had my AMEX Platinum for several years now and have earned my MR points the hard/stupid way. Dollar by dollar spent. Years later, now I am an FT'er and a little smarter, and I see everybody talking about these 100,000 50,000 and 25,000 point deals. Is it too late for me to take advantage of any of these? When I read about stuff like this, it just makes me realize how silly these point systems are and what a sucker/ideal customer I have been over the last few years for AMEX. I just pay my yearly membership fee and accumulate points, but at rates so tepid, that it is really no cost to AMEX. How do I take advantage of all of these great points offers? TIA.

One possible approach:

Look for a good deal on Delta Skymiles Amex (assuming you haven't had one before--and watch the mail for special offers) get the Delta card, transfer your MR points to Delta, cancel MR card, go on a trip first class.

By the way, Amex is often open to negotiation on annual fees, hands out bonus miles etc if you call to cancel. You can accept bonus and still cancel later on.

One possible approach:

Look for a good deal on Delta Skymiles Amex (assuming you haven't had one before--and watch the mail for special offers) get the Delta card, transfer your MR points to Delta, cancel MR card, go on a trip first class.

By the way, Amex is often open to negotiation on annual fees, hands out bonus miles etc if you call to cancel. You can accept bonus and still cancel later on.
What sort of deals are offered to sign up for the Delta Amex card? Enough to make it worthwhile for a non-Delta flyer to open an account?

MR can be swapped for DL miles or used for other purposes, while DL miles earned with the card or flying DL can only be used for DL and its alliance partners.