Maybe Apple got the standby thing right from the get-go. Android didn't. My first tablet drained so fast, I had taken to shutting it down on longer periods of inactivity. Nothing to do with battery chemistry or capacity, thus was all software.

My replacement, a Transformer, seems to use no power for even days on standby. Even with a faster clock, it seems way ahead of what I've heard of the Surface RT. The good news is, they're similar enough hardware, this might be a patch to the Surface and/or WinRT. First place to look: Android uses the tiny 5th processor in the Tegra 3 during standby. The Surface, not yet.

As for the Pro, sleep mode on regular windows may be more evolved, but with hotter hardware, that may just take some time...