Thanks for the responses. Nigel, that's exactly what I was looking for.
on1aag, I have been looking over PLL datasheets and did see that they would output a voltage like I wanted. However, I noticed that only those that operate around < 10 MHz offer that. All of the higher frequency ones just output the XOR pulses of the two frequencies. This is just from me looking through the DigiKey catalog. I'll most likely just go with the lower end PLL to get comfortable with what I'm trying to do at lower frequencies, and then I can evaluate if I really need the higher frequency.