Looking at Chris' list, there are some impressive names. I think my first choice would be Mike Abbott, the Penn offensive last year was very impressive, and he has ties to the program given his brother played for the Orange. His work at Colgate I don't feel is overly impressive, and I don't know anything about his recruiting prowess, but looking at all the candidates I think he would be the most exciting choice.
Chris makes a good argument for Kyle Georgalas - he has experience coaching all over the field (something that Donahue has), and has ties to upstate New York. Of course the Army offense has never really been overly productive on offense so it might not be the right fit.
Scheinder and Kirwan seem unlikely to move - Kirwan would seem to be making a lateral move and I doubt we could get a UMass grad to leave UMass for a job that would not be a promotion. Also, count me as one who would be against naming someone a coach in waiting, so much can change from year to year and it almost never works out.
Now, if Desko found the next Kirwan, a DIII coach doing something innovative and exciting at a lower level that could work on the D-I landscape, then that could be someone they should go after. Amherst, RIT and St Johns Fisher were three high scoring teams in DIII last year that were relatively local to SU. This was a very rudimentary investigation, but could be worth an interview.
Have heard the arguments for Will Manny from Carc and Chris, but I don't know if I buy it. He doesn't have a lot of experience, and not sure exactly what recruiting contacts he has. I know it would be considered "cool" to have a professional player on the staff, and the staff could certainly use some youth, but I don't think those should be the main selling points of an assistant. Again you are taking a leap of faith with the position, but Manny seems like a big risk.