Although I also wish that I could do some serious work on my tablet / smartphone, you simply can not do it (too small screen => primarily wasn't meant for this kind of job, but it's great in mobility and therefore "valuable information on the go").
Tablets & smartphones are used to consume / present information and PCs / workstations are used to generate that information.
I have also tried all kind of Office software (QuickOffice HD, Polaris Office, Docs To Go, GDocs,...), but reality is that generating information on Android is 30-50% slower than on a 20" monitor with keyboard & mouse hooked on a PC.
Yes, you could make a new office software on Android that would need a keyboard, mouse & external monitor, but that would defeat the purpose of mobility.
And sadly there is no such good software on Android with so many funtionalities that are found in Microsoft Office.
IMHO you can do up to 30 minutes of work without problems, for anything above that, please do yourself a favor and use a PC.