Well, you already have a good mix of lenses in your bag right now. You have the excellent 70-200 2.8 IS, which is already a great portrait lens. While the 85mm and 135mm are great lenses, they do overlap your 70-200. Also, the 300mm f/4.0 is a great lens as well, but the 1.4x TC with your 70-200 gives you a 280mm f/4.0 with little to no image loss, so the 300 f/4.0 seems a little redundant with your 70-200 and 1.4x tc
What I would suggest is to upgrade your camera to a 40D, or upgrade the Tammy to a 17-55, 24-70, or 24-105L. You could then sell the Tammy or XTi, and pick up another little toy, such as a 580EX II (which you don't currently have)
I agree with updating your camera to the 40D, selling your XTi and buying other stuff like a 580EX II. You'll still have a little left over to take the wife out to a nice dinner!





