I defininately agree that you won't find one bike to do it all. If you're reluctant to go with drop handlebars, give them a try at least, I'm going to have a hard time going back. Depending on the position of my hands, I think sometimes I have better control and more grip with the drops on my Jake. In fact, I've been thrown and still had my hands on the bars.
I just like the cyclocross because I like to go and hit some serious mud and I need something I can get to work on. And yeah, I school the MTB'ers on some local trails, both uphill and down.
bsyptak has a good observation on the Cannondales. The headshock is great and the bike is a great all arounder. In addition, they've VERY well made. I'm not partial to the gearing (a little weak if you ask me @ 22/32/44), and I've read that it's friendly towards full fenders. It's probably a little more MTB than Road if you ask me. It's a $1700 bike, but it's a Cannondale.
Also in the flat handlebar, all arounder category you'll find Kona's Dr. Dew, which I came pretty damn close to purchasing. A bit better as far as gearing, but no shock (which I find pretty useless anyway). It's nearly the same in the gearing dept. as my Jake, except the freewheel has an 11 on it instead of the 12 my Jake has.
I'm also pretty hawt on the Specialized Sirrus bikes. Nice componentry, more of a street bike though. Now that I'm scoping them, I want one again. Slap me.
There's not a hell of a lot of way I could do 'cross on a bike with 29'ers unless the rims had more spokes than common sense dictates. 29's are great for XC, but that's a lot of horizontal rolling resistance on those tires, which would make my morning commute kinda suck.
I just found that I could fly better on road and off on a CX bike. And it's all about flying for me.