Thanks for the suggestions @MAcsWork and @cwa107. I'll look onto it.
@Zoolook I haven't done a well controlled comparison yet. I use Google Apps on Chrome for work from home office and so have never had to question the power consumption. I might have firefox or safari open at the same time for "personal" surfing from time to time, or just another chrome window. Had a MB Air 11" for desktop on the go.
Recently I consolidated my operations into my new favorite non-living object, my 15" MB Pro (Processor 2.2 GHz Intel Core i7, Memory 8 GB 1333 MHz DDR3, Graphics AMD Radeon HD 6750M 512 MB), and I have been slightly disappointed in the amount of "away from the power cable" time I'm getting.
I use a couple other power/graphics intensive apps (Parallels 7 Running quickbooks premier, Sketchup Pro 8), but no video editing, gaming, or other graphics-intensive applications. I suspend the virtual machine in Parallels before sleeping, close smaller apps I'm not using for a while, etc... But I seem to only get about 3-3.5 hours of working time, net.
So my question came not so much from having a sense of browser comparison, more so from initial troubleshooting about how to configure my settings to get the most mobility.