Why not try the newly built hotels which are not due to open until later this year or early next year?
I presume everything in Docklands is already block sold, but there are new properties to open on the Westfield Stratford site, as well as an aloft at the Docklands Excel. I would also try the Holiday Inn Express in Greenwich too...even though it is on the wrong side of the river, it isn't far from the Olympics on the Jubilee Line.
I would definitely look for hotels using the tube, overground and DLR maps.