Unfortunately, KOffice is out of consideration. True, it can be installed on a tablet, but it is way too heavy in terms of space and performance requirements. Also, it does not take into account unique input requirements of tablets.

AbiWord/Gnumeric pair looks like a much better bet, after somebody polishes them for long enough. May not happen though, as nobody is paying for this work. Texrat, it is something you might talk about with your management: the cost of partially supporting a developer or two to work on AbiWord/Gnumeric is much less than the benefit of having these tools working properly on these tablets.