The Amex SPG card has two separate signup bonuses going on now. Both offers are available via referrals.
25,000 Points
The original SPG offer has always been 25,000 SPG points after signing up and spending $3,000 with the personal version and $5,000 with the business version. It has gone up in the past to 30,000 or even 35,000 points, but those offers aren’t currently available.
Find Your Referrals Here for 25k Offer
When logged in, this link should get you to the referral page for all your Amex cards where you can refer a friend via email. Scroll to find the SPG card.
2 Free Nights
The other SPG offer is to get two free nights at any category 1-5 SPG property worldwide after you spend $3,000 with the personal version and $5,000 with the business version. This is currently the publicly available signup bonus for these cards on the Amex site.
Most people will probably prefer the SPG points offer, especially given that SPG points now transfer to Marriott at 1:3 ratio for some sweet deals.
Find Your Referrals Here for 2-Night Offer on SPG personal and business cards
(Hat tip to Dannydealguru and branespload on r/churning for letting us know about this new referral offer.)
Final Thoughts
As noted, most people will probably do better with the 25k offer. Also, you might consider waiting to see if SPG increases the bonus to more than 25k at some point in the future, given that these bonuses are once-per-lifetime.
When I logged into my SPG business card, it showed the ordinary 25k signup bonus, alongside all the other referral offers on my other Amex personal and business cards. When using the special 2-night link posted above, I got the new referral offer with the 2-nights signup bonus.
Both will give the referrer the same 5,000 bonus points per referral, up to 55,000 points per year.
Please don’t leave any referrals in the comments of this post. Instead, head over to the SPG referral thread and follow the instructions there carefully to leave a referral. You can also specify which offer your link has.

