Well, I felt as you do for the first month or so that I had mine. I read around, asked a few questions, and didn't really see anything terrible compelling about rooting. But I'm a born tinkerer, so once the honeymoon phase was over, I got bored and wanted to do stuff
I started out by rooting - which mind you was easier for me since one-click rooting worked for DI01 firmware... I have no idea what the current method is for DL09. After I rooted, I didn't do much initially. Removed a few bloat apps, installed a few novelty apps like wifi tether, etc.
After about a week, I got bored again and decided I was going to flash DJ05. Getting my GPS working was a big factor in that decision as well. So I did a bunch more reading to prepare and then flashed CWM, then the DJ05 modem, ROM, and kernel. It (mostly) fixed my GPS issues, but aside from that I didn't really do much else with it at first. Of course, you're on DL09, so it's my understand that you shouldn't have GPS issues.
The next thing I did (only took me a few days to get bored this time

) was flash an undervolted kernel. Specifically geeknik's stupidfast 1.54 kernel. I still believe this has been the best kernel I've used as far as battery life goes.
After that I stood pat for about a month until I started getting into themes and voodoo kernels last week. I flashed to jt's superclean 0.9 ROM in the process - mainly because it comes deodexed, which is a requirement for most themes. I've also come to appreciate some of the other subtle changes, though I wouldn't say any of them blow away the stock rom.
I *really* like the gingerbread theme I've settled into. Voodoo/lagfix is pretty nice, but I'm still a bit unsure just how much difference there really is vs placebo. Voodoo sound is quite nice, though. If I could just find an issue-free voodoo kernel that gives me the kind of battery life that stupidfast gave me, I'd be 100% content until 2.2 rolls out. That's not to say that I'm not happy with any of the options I have right now, it's just that none of them are "perfect".
I'm not sure if any of that really helped you or not but there's my brief Fascinate history