I know next to nothing about strings, and there are so many choices. I am ordering a Wilson Blade (pink) for my wife for Christmas. Which would be a decent string in the $11-20 range to have that racket strung with from TW? She hits a very flat ball almost all the time, and doesn't use much slice or topspin. Is there any other information necessary for a basic recommendation? Also, she is a solid 3.5 now, but was in the past, and trying to get back to a 4.0 level. Thanks for the help!