As with most affinity cards, Citi offers an incentive for you to sign up for the card. When you spend $2,500 within the first 4 months, you will receive 2 weekend nights stays. The stays applies to standard rooms.
Question is how much is the weekend stays worth? According to Citi's website, they are good for category 1 to 7 hotels. If you were to check out Hilton HHonors website, you'll find that you need 50,000 points for a category 7 hotel. That means that the bonus is worth potentially 100,000 bonus points.
You could obviously use it on a category 1 hotel (which requires 7,500 points per night). But that would be a waste.
In constrast, the American Express Surpass Card gives new cardholders up to 60,000 points in sign up bonus. You earn 40,000 when you get approved and an additional 20,000 after your first $3,000 spend on the card. That will be enough for one night's stay in a category 7 hotel.
So the Citi version is definitely more valuable.