Spinrite will scan the entire disk - considering the current read speeds, I'd estimate that to be in the thousands of hours range at the moment.
Yeah that's the big downside to Spinrite. If anything can fix the drive it's Spinrite (even if only temporarily), but unless you have some extremely valuable/important data it usually won't be worth it because of the sheer amount of time it takes. You can get Spinrite to only work on a single partition, but AFAIK you can't select individual directories, so if your whole drive is one partition it will still take forever.
I was working on someone's laptop and it took almost 3 weeks for Spinrite to repair it enough to get most of the data off of it, and that was only a half-full 320GB drive. It really depends on how much of the drive has problems too, but if you are having trouble copying a bunch of random files chances are it's a widespread problem with the disk.
Sorry I don't have a better answer, but if such a utility (one that works quickly and is still effective) exists I've never heard of it. There are always those data recovery services where they actually read data straight from the platters, but as I'm sure you know those services are VERY expensive.