If you were really precise, you could tune your assist based on distance. You could get a pretty sick change in angular momentum relative to the sun since you w

If you were really precise, you could tune your assist based on distance. You could get a pretty sick change in angular momentum relative to the sun since you wouldn't have to worry about hitting atmosphere or terrain. If you're far away you feel nothing, if you're too close you join the singularity, and everything in between is gravy. Imagine getting a 1970's style planetary alignment, going with a Voyager style slingshot and your final assist is a couple thousand miles away from a black hole.