Surrounds for Thiel 3.6 system?

You might want to consider the Vandersteen VCC-1 center channel speaker. It has a single, high quality 6.5" coaxial speaker, so it provides a "point source" type of sound that should match well with the Thiels. The VCC-1 also has a proximity switch (on the back) which allows you to contour the sound for how the speaker is placed -- close to a boundary (like on top of the TV), or stand-mounted in front of the TV. With regard to the side/rear surrounds: you didn't indicate if you want dipole or direct-radiating models. I am currently using a pair of Coincident Technology Tiumph Signature speakers as rear surrounds, and am very pleased with them: above-average efficiency, very clean, and close to full-range.

I have to agree on the SCS's. I have 3 of them used as center and surrounds. They have been used along with 2 2's and now 5i's. They integrate very well. Extremely well built coaxial speaker.

As an update, in a fit of pique I picked up a pair of the Definitive Technologies BPX dipolar surrounds to go with the Thiels. (Used, great price, couldn't resist). Love the speakers, but they are definitely not a particularly good voice match for the Thiels. So far that has bothereed me not a bit and only time will tell whether it will begin to in the long run.