I don't really see using sense if you aren't *using* sense (launcher).
I use a Sense ROM (MikG) with GO Launcher and do this for a few reasons:
1. I like the Sense dialer and contacts application. When I tried CM7 I was using GO contacts/dialer which was better than the default, but seemed to be a bit laggy to open and close. The Sense dialer seems to launch perfectly.
2. Sense also does better syncing with Facebook contacts and pulling in their pictures. I tried joining contacts in the People app but in CM7 it seems like I still had problems here and there.
3. I hate the default Android keyboard and have become accustomed to the HTC_IME keyboard. Yes, I can flash this keyboard but it doesn't include the arrow keys so the keys are wider and it's like using a whole new keyboard. Also tried Swiftkey and Smart keyboard. I could probably get used to Smart -- my only complain was that the key to toggle symbols was on the left side of the space bar instead of the right side (which is where it's at on my HTC keyboard). I could probably live with that though, it's just not what I'm used to.
4. I use the HTC Flashlight app quite often and it's just better than Torch. There are 3 different intensity levels and you don't have to turn it off and then agree that you might break your phone every time you want to change between them.
5. The MikG lock screen uses the Sense 3 lock screen which allows shortcuts on it. I prefer this over gestures -- I had several times where my gestures weren't recognized unless I drew them perfectly.
There are probably some other reasons too that I can't think of right now. My battery life is actually pretty darn good MikG. I have even posted some videos of my battery life on youtube. I got 32 hours with 50 minutes of voice calls, 30 minutes of words, 41 minutes of GPS, bluetooth on 100% of the time, etc.
I have never tried flashing Tiamat but I heard it's great. If I can fix some of the remaining issues I have with AOSP I might try it. Maybe when CM9 comes out I'll give it a shot again. I have really wanted to like CM7 and tried but always wind up back on MikG.