I suppose one of the parameters to consider is the collar type. Assume a turndown mid-spread collar.
Here's the grosgrain diamond that I have. IMO, the LPN stuff is too expensive.
Summary of bowtie styles:
Dude! A big no on the pre-tied.
This is the best instructional video I have found - give yourself a half-hour to practice and you'll get the hang of it: http://www.youtube.com/watch?v=VJv4Qh7zR3E