If it's an exceptionally large room you could use the ramps method, but you have to be careful then not to have miners dig ramps under unmined ramps on the level above. That leaves a floor behind that promptly falls and crushes your dorfs or at least knocks them out.
Indeed. When I ramp-remove (e.g. my current long-standing mega-project, which is taking a lot of playing time for not very much game-time), I often do the ultimate micromanagement by setting ramps around the perimeter (when taking away outside hills) or the centre (if mining out caverns) and then as this external(/internal) ramping is completes around any part of the border, I designate the exposed areas.
Of course, with the take up of new ramp jobs being biased towards those that are adjacent to a just-finished ramp, and then a preference for northerly/westerly positioned ramps if necessary, you can see how with a number of miners wandering onto and out of the worksite, it all gets a mite muddled, so I've come up with coping strategies.
I aim, in the end, for external ramp-removal to end on a single lone ramp (or a 2x2 square designated to be ramped, which itself ultimately degenerates into a lone ramp without any fuss), which I can [d]esignate for [z]ramp-removal (just to keep things tidy, not necessary), and then start on the level below. Or I could even start on the level below under any successfully ramped Z+1 spot (or one away from the edge, to allow ease of movement by both the rampers and other agents wishing to route across my worksite) without risk of cave-in. Although this is one reason why I wish there was a "down-ramp" designation option... You could apply it to any spare square without having to ">" and "<" your way through the levels to make sure you're not digging in a problematic tiles (also, avoiding any trees that you haven't yet harvested, when still working at 'ground' level or anywhere else with two z-levels or more of soil laying undisturbed for long enough).
If I wasn't so anal about it, I could of course just designate ramps across the whole lot, and ignore all the isolated ramps that end up getting left on any level but the lower one (they don't cave-in, once dug, although there are other dangers).
I'm wondering whether to upload a map or even movie of my current mining operations.
The whole 'quarry' is approx 125x125, with raw bedrock left in pillars (and a central pyramid) and currently varies from about four or five levels below the original surface at the moment to some still largely untouched plateaus that I'm nibbling away at (though I think I've rid myself of all tree-bearing soil) from a terrain which originally varied by a couple of Zs at the most). Over the seven dwarf years, the four miners have between them (in-between injuries when I haven't been too careful, or failed to shield them from combatant archers peering down on them) mined out maybe 50,000 stone units (and an unknown number of soil ones), but could have done more if I hadn't been supporting a working 'side fortress' dug into the walls of the pit and building loads of walls/maintaining a trap'n'breed facility/water-management/keeping a trading post up and running/protecting myself from sieges and and lone hostiles/maintaining a largely non-dissatisfied (and ever growing) non-mining population.