Tom,

What did you end up choosing for your rear derailleur? IMO, even if they don't "match," I like things to compliment each other. Because you're doing a triple, you probably want to have an ATB/MTB front derailleur- so the choice comes down to what kind of class you've chosen for the rear. My personal favorite front derailleur is the Suntour Mountech. If you ended up choosing the Ultegra RD, depending on the year, the corresponding triple FD would be a good choice. Other really swell silver Shimano triple FDs are the MT-60 and the Z206.

You can also never really go wrong with Shimano's Deore XT or Suntour's XC Pro (or XC Comp). (But not MD- Micro Drive- made for small chainrings.)