I personally install and use Snow Leopard (with Rosetta) in Parallels 7 in Lion, so that I can run my PPC software concurrently with my Lion environment. I am not disposed to use the so-called "dual-boot" method of running Snow Leopard, primarily because my 2011 Mac Mini will not boot Snow Leopard (that being said, there is a thread on Macrumors that did accomplish that goal, but that is not my preference).
Snow Leopard and Rosetta operate very well primarily for those applications that I use: Microsoft Excel and Word 2004, Adobe Photoshop CS and a smattering of other apps on a much lesser used basis. Quicken was my initial need as I used Quicken Deluxe 2002, but in March 2012, Intuit released Quicken 2007 for Lion (and now Mt. Lion) for $15, and I was able to update my Q2002 data to Q2007 levels and I use this program in Lion very successfully.
So then I read your initial post:
First you complain about the lack of ease by which one can install Snow Leopard client into Parallels (you did not mention ever, which version of Parallels you were using); I believe your term is "frig!" It is well known and well documented by Parallels (and all of the other virtualization products) that they only officially support the installation of the Server versions of these Mac OS'es.
Perhaps your method, moving a clone of Snow Leopard over to Parallels operates more inefficiently than my method, which is just a pure install of Snow Leopard.
You then go into several inefficiencies of using Snow Leopard in virtualization such as no cut & paste across the environments. My understanding from several sources is that the upgrade to Parallels 8 solves most of these problems. I am still using Parallels 7 and use alternatives to cut & paste.
I will admit I avoid ever letting the main environment go to "Sleep" and shut down my Parallels environment before this can happen, so perhaps I avoid the two "sleep" problems you suggest. With this in mind, I do use Shared Folders with much consistency.
This is why I opened my original reply with the fact that you were incorrect, since Parallels 8 solves most of these problems. Since you did not mention a version number, I was working on the idea that you were most current, unless you specified otherwise.
You then suggest "in short" your motivation for using Snow Leopard in Parallels, which is the need to restore Rosetta capabilities to run your PPC applications.
Since this was the motivation for you posting to this thread, I pointed you to my post #31, which speaks directly to this issue.
Lastly, your last comment seems especially harsh on Parallels, especially since you do not offer an alternative competitive source (VMWare, VirtualBox, etc.) that does not also suffer these same problems. So I had to ask myself, why are you picking on Parallels, when they do offer a good source for almost all of what you complain about (except maybe the SLEEP problem, which I bet further research would solve).
Save your payday:
You can download the 14 day free trial of Parallels 8 from their website.
But I think the more important issue for your sense of success and usability would be to do a fresh install of Snow Leopard into Parallels 7 based upon the instructions linked in my post #31 and see if that works more efficiently for you. Then, if that is successful, upgrade to Parallels 8.