How much do you spend on it each year?
How much is your typical vacation?
Blue Sky gives you $100 credit for every 7500 points, but you do get double points on restaurants, travel, hotels, etc.
In 2012, the total charges were a little over $75k. We put anything and everything possible on the card, so it adds up fast. We got double points on a lot of that.
I usually redeem $800 to $1700 to take trips. In some cases, the points all go to airfare if it's a big trip. It's just for two people, no kids yet, so it's very easy to go to the beach or Vegas all on points.
The only disadvantage of Blue Sky is that you can't immediately use points to purchase the trips. You charge as you normally would, then submit a credit request the following statement period. So you need to be able to pay the bill before getting reimbursed. Most people don't like that, but I do. It helps keep things within budget.
I have a trip for Memorial Day that I will use points on. I will pay the bill for May out of pocket, then a credit will be put on for June. My June balance will be nice an low.