"Soft and large" --- this is often a product of applied reverb.
So you'd get the tone and timbre you want with the osc's, and the slow lfo modulation to relieve the boredom, then run it through a fairly large reverb setting - large hall or cathedral with longish reverb, quite wet. This will tend to both soften all edges and expand the whole sound to fill the stereo sphere. It helps to use the best quality reverb to get a real smooth effect.
But multiple voices can also be used to make something large too. Keep the voices smallish so they don't overpower each other and pan them differently. ......... then slap on the reverb
Of course, choosing the voices carefully is an art.
Another approach is to duplicate your pad on another track (or tracks) and treat that a bit differently (effects) from the original pad. You can build up a richness and largeness that way.
Just some things that came to mind.