I'd say the main issue (in the debugger) is that the presentation method is poor. An unrolled list of everything, without so much as the size listed next to it, means it's impossible to find the thing you want due to single byte variables being saved and listed in the drop down. Being able to view memory allocated by drivers etc. that isn't in CPU space is essential though, the hoops people were jumping through prior to that (fake regions in drivers etc.) were polluting the codebase badly (to this day some of those workarounds remain in untouched drivers)
A tree view would help, even just showing the sizes so you can see at a glance which ones are likely to be RAM areas would help.
A menu option to 'save region' when you have a view open would also be great, having to remember the syntax in the debugger and type it is a pain.