Do Bigger Speakers Mean a Bigger Window?

Ease of driving only makes a difference if your amp is too gutless to drive a more demanding load. Some very difficult to drive speakers cast massive soundstages, but you need an amp that doesn't go flacid into a 2 ohm load or less. Casting huge images is what speakers like Wilson W/P's do very well. 

@kosst_amojan, yes I can remember reading Ken Kessler writing about how the fabulous Apogee Scintilla's with their 1 ohm load only came to life spectacularly with Krell amps.

Unfortunately reading about them is as far as I will ever get with such audio exotica. There's no denying that power is important especially if you enjoy a wide range of musical genres, and it never hurts to have too much as long as you're careful with that volume control!

Really, it's a lot of much more nuanced factors than sensitivity/efficiency, size of speaker, types of driver, or amplifier power. Amplifier bandwidth, damping factor, feedback and how it's implemented, the reactivity of the speakers, how well they're damped, and a whole bunch of other factors. The room is also a big factor. I've got Focal 936's. I'm driving them with a modified Pass F5 making about 32 watts. Those are kinda small, tough speakers to drive, and that's not a monster amp. They have no problem casting a towering, enveloping, deep soundstage with plenty of muscular bass. 
If there were simple, easy rules of thumb to get this quality or that, then all of audio would be just those things. But for every claim that you need this amp or that speaker to get this quality or that, there's some glaring exception to that "rule". Much of the secret is in the technicalities of how the amp, speakers, and room jive. 

If you place a pair of small speakers correctly (well away from the back wall and the side walls), you can achieve an amazingly large soundstage.  In that sense, they can sound "big".  That actually is the case with any sized speaker, proper placement gets you a big soundstage.  But, there is something about the weight, sense of ease and effortlessness that one gets with physically big speakers and drivers that is missing with most smaller speakers.  If one listens at reasonable levels, small speaker certainly don't sound like they are straining in their delivery, but there is something not quite as convincing about the size of the musicians and the stage with small speakers even when the positions of the instruments are the same.  If at all practical, I would take large speakers over most smaller ones.

@kosst_amojan, yes it can be a very complicated business getting good sound.

Some get lucky with their setup and room from the get-go. They seem to be easily pleased with modest equipment, whilst others suffer for years on the treadmill to audio nirvana, chasing their tails and swapping equipment on a regular basis.
I should know, I've been there. Might still be there?!

And then there are some who even enjoy being on the treadmill to audio nirvana!

@larryi as I've got to know myself better I've also come to the conclusion that I prefer larger loudspeakers for their ease of listening. I must admit though, I've no experience of using subs despite finding the idea of relegating the heavy work away from midrange units quite appealing.