I think the SPG is a solid choice but the only hard part is you need to decide if you want to wait for it to increase to 30k or just get it now. I personally wouldn't wait since it tends to increase at the very end of summer and its still very valuable as is - for redemption or transfers...Or you could do a personal now and business later and spread the apps out. Your PRG doesn't count against your 4 card limit with amex either so there's nothing to sweat as far as 'pushing it' with amex goes.

Since you have the Citi Prestige, the premier is a very logical choice too. You can combined those two bonuses to the Prestige account and then use the 100k+ points for a nice discount on AA flights, or whatever airline you'd like to transfer to.