I do not currently use room treatments, but would like to in the future.
There are 2 main things I would be looking for:
1) affordable price
2) acceptable asthetics
Not having a dedicated theatre room and a large budget means it's usually tough to find nice looking treatments at a good price.
As far as looks, a 2" think panel that is effective and has nice fabric would probably be acceptable in my book, however a 4" thick panel would never fly in my living room. I have also looked into bass traps - and I think a corner trap would be ok asthetically provided it's as compact as possible while still offering sonic benefit, and again, has some nice fabric options.