I think this is completely sensible. My workflow for post-processing looks something like this (I usually have about the same number of photos from a shoot):
1) Initial triage - I go through every photo I took during the shoot and immediately discard the junk. Photos that are out of focus, subject blinked, blurry, etc., immediately get trashed (if you work with Lightroom or Bridge, you can "reject" a photo so that you don't see it any more, but the file isn't physically deleted). During the course of this, I make mental notes of photos that I particularly like for my second pass through. This usually takes no more than 15 minutes.
2) I then go back through and do a secondary triage; this time I'll start comparing photos side-by-side to see which one I like better in terms of composition, and how much I think I will be able to improve the photo during post. Sometimes I'll do a test crop, or tweak a few sliders, but I almost never save this, it's just experimentation. Of the ten or so different photos I took of a particular subject, I'll keep the two or three that I liked the best, and reject the rest. This process will take longer than the initial triage, maybe 30-60 minutes.
3) Now I begin post-processing in earnest. At this point, I'm trying to get images that I will keep, so I'll spend 5-15 minutes on each photo. However, I've usually pared down the list of photos to a more reasonable number at this point, so I'm not so concerned about the time I spend on it. Once I've gotten a photo of the subject that I like, I reject all the rest. (On rare occasions, I'll keep several photos of the same subject if I can't decide which I like best, or if they are drastically different in some way). This is obviously the most time-consuming part of the process, but I typically spread the work out over several days, spending an hour or two each evening.
4) Once I've gotten all of the photos processed that I'm pretty sure I'm going to keep, I'll hide all of them and go back through my rejects to make sure there wasn't some gem that I missed, like mattdm suggests. Usually I don't find anything, but every once in a while I'll catch something I like better. Then I'll physically delete all the reject files, and copy the others into my permanent directory structure.
Using this process, I can go through 200 photos in about three days, depending on the subject matter and how much work it takes to do the postprocessing (if I have to remove tons and tons of powerlines, it takes way longer than if the photos just need brightness/contrast tweaks). I'll also bounce around in the above routine; sometimes I get tired of step 2 and spend time in 3, and vice versa. Sometimes I'll reject a file in the first pass, and then decide later on that I want to use it anyways. But by-and-large, this process ensures that the only photos I'm going to do heavy post-processing on are the ones I'm actually going to keep.