An addendum. You can get the United card with United miles and then get the Chase Sapphire card and transfer Chase points to United. Several different cards allow you to transfer miles/points to different hotels and airlines. That's why I suggested figuring out what you want to do and then mapping out a strategy to get there.

If a really good offer comes along, grab it even though you might not have a use for the miles or points. They can come in handy in an emergency. You may want to visit a sick parent or go to a funeral at the last minute and having miles may make an expensive trip reasonable.