If you want painting advice, I don't think I would look here. I've been
in the business for over thirty years, and everytime I post a
suggestion, some know-it-all DIY'er tells me I'm wrong. That said, the
answer to your question is, use a 3/4 inch nap roller and flat paint.
Also, use an adjustable extention pole with a roller screen inside a
five gallon bucket. And finally, keep pressue on the side of the roller
that isin the unpainted area, then the side with less pressure erases
the roller marks. Sure an airless is good for ceilings, but the learnng
curve on trigger pull is quite severe and may have you rolling behind
the sprayer.