With your situation you might want to consider a cash back card; since you don't spend a lot on your card it will take you a long time to accumulate enough points for a reward. As for Chase Sapphire or AMEX Blue Sky, do you currently have a Visa/MC? If your looking for a single card option 2 things to keep in mind AMEX isn't accepted everywhere; also with Sapphire it has no preset spending limit so that might cause issues with your credit utilization and hurt your credit score.

Since you mentioned you want to travel outside the US you might want to look at Capital One with a Cash Back card; They currently don't have a FOREX fee for purchases abroad.