We're doing a bit of both, with the known and quantifiable (web hosting management) supporting our pioneer efforts to be part of a new and almost entirely unsettled territory (cloud computing). I wouldn't necessarily recommend it over other tactics, but it's what fit our business and our existing codebase--we launched based on an old and well-established Open Source project and the existing code greatly directed our first couple of years in operation. But, we also know that becoming a leader in a well-established field, full of well-funded competitors, is not necessarily a trivial endeavor.
So, while we think our hosting management products will be a nice source of revenue for years to come, it's the combination of those tools with cutting edge stuff in the virtualization space that will allow us to lead rather than follow (because no matter how good your products are in an established market, you'll probably always be playing catch up in the mind of the market).
I also think you're underestimating the amount of interesting work that can be found underlying seemingly mundane tasks. I've found that data analysis and visualization can be a really interesting and fun pursuit within systems management software, and it's an area that brings tears of joy to customers (seriously, people wet themselves over graphs and charts...if you also add export to Excel or CSV, there will be fainting).
Regardless of all of that, you have to solve problems that customers want solved. If you're doing that, the harder problems are better, if you are willing and able to solve them faster than your competitors.
But, if you are starting a business rather than a research project, you need to make your decisions based on what people want rather than what you want to work on. You cannot start from "here's a cool technology, let's figure out a way to sell it", at least not generally. You must start from, "Here is a market that is being poorly served, and I can serve this market well." If you can fit, "by building interesting and cutting edge technologies" into that sentence without breaking it, then you've got yourself a winner.