1. The real value of Rewards+ is the 10% rebate on point redemption. It adds 10% (actually 11.1%) to all SUBs and earn rates. In other words, Double Cash effectively earns 2.22 TY points. Prestige effectively earns 5.56 TY points for restaurants, etc.
2. Most people use Rewards+ at coffee shops to get 10 points per cup. But since you have Prestige, you already do better than that on coffee shop purchases > $2. If you buy lottery tickets one at a time, Rewards+ makes sense there. But overall, it's very difficult to amass a lot of TY points ten at a time.
3. I would argue Amex Gold is a better restaurant card than Citi Prestige UNLESS you have $200K at Citi (i.e. CitiGold). CitiGold brings down the Prestige AF to $350 total, or net $100 after travel credit. Otherwise, the net AF is $245. Amex MR and Citi TY are worth roughly the same to me. Assume 1.7 cents. Amex Gold net AF is $30 after airline incidental and food credits. Prestige earns 5x vs Amex 4x. So $70 net AF differential divided by 1.7% = $4,118. If you are CitiGold and spend more than $4118 at restaurants, Prestige works in your favor. This number comes down if you have Rewards+ and earn 5.56x TY points on restaurant spend. It also comes down if you assume 2 cents per point for both MR and TY. If you aren't CitiGold or don't spend $4K per year on restaurants, then Amex Gold > Prestige for restaurant spend.
There are other factors to consider. Amex Gold is also a great grocery card. Citi Prestige beats Gold on Airfare 5x to 3x, but Prestige offers no travel insurance perks while Gold does. Prestige offers 3x on cruises and hotels, which Gold has no other earn rates. Prestige's main superpower is 4th night free, but it's limited to twice a year and you have to use their portal which means your stays won't count for status. Gold offers $100 off on two night stays in their (limited) Hotel Collection.
4. The best use of TY points is travel partners. I like to wait for promotions before actually transferring the points. "Get 25% extra LifeMiles," etc. If you aren't traveling soon, you have time to wait for these specials. Figure out which transfer partners you can use. For example, LifeMiles is a partner of United and you can book United flights for less miles on LifeMiles than you can on United. A flight that would have cost $400 or 25,000 miles on United cost me 20,000 miles on LifeMiles (2 cents per point).
