Though I'm not a big fan of Klipsch, you may want to give their center channel speakers a listen. They're slightly bright but clear....may match OK with your Thiels. For surrounds, my feeling is that you can get away with many different speakers because they are mainly there for special effects. The only downside would be if you do a lot of listening to music in surround mode in which you'd want a closer match. Hope this helps.
Milo's got it/go with it. Sure..., It's a comprimise,but you know that. Plug/and play /enjoy!!
I'm wrassling with comming up with some surrounds to go with my 2.3's. I'd love to have a pair of Thiel's Powerpoints, but $2.4k for those plastic little jobbies has to be a joke. So much so that it almost pisses me off for having bought Thiels in the first place. Really. I'm leaning towards something along the lines of the NHT Super One XU (so I can wall mount it, as I'm real short on space). I'd love to take the time to find something that I thought was voiced similarly to the Thiels, but I am beginning to convince myself that it is just not that important for the rear surrounds. As for a center channel, I think I am going to buy a silly expensive TV and configure it as the center channel until I come by enough room to convince myself that a legit center channel is worth the duckets. Come that day, there are spots around here where I could pick up a single SCS2 for around $600. I might consider that.... Just my thoughts.
When I had Thiel's (3.6's, then 6.0's) i used an older pair of Thiel SCS's for the rears and a SCS2 for the center. The setup worked really well. Matter of fact I am still using the center and rears with my current setup. You can find the SCS's really cheap if you look around and the SCS2 like Mezmo said for around 5-600$.
I have Thiel 1.5s and an SCS2 in the front, and use the Atlantic Technology 454SR for surrounds. Not an exact match in timbre, but I only notice the difference when cycling pink noise through the channels. For program material, it has always sounded great.
For the Buck, in a dirrect firing monitor, I think the NHT 1.5 monitor (mounted properly), is a superb sonic match with the 3.6's! I've had Thiel 2.3's and 1.5's, as well as the NHT 1.5's, And, I think mounted properly, this would be a very close (and cheep) match for the $ ($600 retail for the NHT's). While the 1.5's aren't quite as dynamic as the NHT 1.5's (you could get dynamight results if you, say, rolled the bass off to the NHT's at about 60-80hz!!!
I have a pair of Thiel original SCS which were designed specificaly for surround. I had a matching center but later sold it. They were matched with a pair of 22's until I sold those as well. The SCS is designed to be placed against the wall. They are very heavy for wall mounting but is possible if you anchor into a stud. Typical Thiel quality, a 2-way coaxial design which is ideal for surround. They are in black ash and in very good condition. Let me know.
I'm using Paradigm Reference ADPs with my CS7.2s and don't feel the need to upgrade. They blend well with the Thiels and provide a nice wrap around effect that I didn't get when using a pair of Matrix 805s. The ADPs are dipoles which mount on the wall up and out of the way. They retail for 900, but you can usually get a good discount on Paradigms.
I had my Thiels set up with an SCS2 for the center and didn't think it matched up very well - a little smoother and laid back compared to the 3.6s. Turns out a Polk CS350LS is a near perfect tonal match with the 3.6s. As for the surrounds, they are probably less critical....
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.