could it be there's no uniform truth to the question? i posted the question elsewhere too and got the following: that's a stain, not a paint. you don't put primer under it, he's right. typically i might put a coat of turp/spirits/etc to make sure there's no mold/mildew/etc that goes unkilled. but with cedar that shouldn't be much of an issue, since cedar is quite resistant to parasites and fungus on its own. however, you could do that. walk around the building and inspect for mold/mildew, you know what it looks like (black or grey spots that seemingly originate from nowhere, thus disregarding black spots around nails from nail deterioration). if there is none, you should be fine with his proposed method. if there is any mold/mildew anywhere, you might point that out and suggest he pre-treat it all with a coat of turp first. note that this is a STAIN not a paint. it will be a roughly 7 or 8 year maintenance cycle, in that you'll need a new coat every that-many years. but the new coat will be fairly simple to apply, just wash dirt away and go, no other prep needed. --- now i'm just totally confused and big time concerned.

The gloss in poly will amp up the color somewhat, but not really give it depth, if that makes sense. Almost like how the stain appears when wet. You're pretty darn close to that flooring sample. If that's your match board, were it me I'd do one more light coat. Hold your sample board next to the wet stain, to guide you to what it will look like with poly. You'll achieve just a bit more depth with another coat, but not excessive. Once the initial two layers or so of stain soak into the wood, anything more won't reach much beyond what the pigments in the stain have to offer. (Kind of like paint: another coat of black doesn't make it darker black ;) Another option: if one more coat doesn't cut it, you can alter your stain ratio, mix up another small batch and raise the amount of the darker color in the mix. If it was 50/50 before, do a batch with 60/40 or 70/30 with darker being higher content. Don't let it sit long or it's going to get deeper on you than you might want. (Test it on some similar wood if you've got some.) With the darker ratio, I'd wipe it on a tread and then almost immediately wipe it back off. So much easier to build stain color depth up than slap it all on and try to remove depth.

"you can't hide the oak grain and pits with paint!" He is correct. Put paste wood filler WILL fill the oak pores and allow a smooth finish. Once you get to bare wood you apply paste wood filler (Pore-o-pac by Behlans is one) is than applied to the wood and allowed to start to set before rubbing most of it off with burlap across the grain. If you are going to paint use natural or a light color filler. After the filler finishes drying you get to sand once again with fine grit to remove any excess filler on the surface. If you remove to much filler (or it shrinks excessively from being thinned to much) you may even need a second coat of filler. You can make ANY wood smooth as glass if you want to work at it. The prominent pores in oak furniture are a 'style' that omits paste wood filler. There are also finish styles that use contrasting or colored filler to emphasize the pores while leaving a smoother surface.

millworkman - Thanks for the reminder! What I'm doing will meet code for rise and run of stairs, which is why I acknowledged that adding 1 1/2 inches to the height of the landing would require adjusting the rise of steps going up and down from it OR removing existing underlayment. Just looking for the least complicated way that leaves the landing structurally competent and I may not have explained very well what I think are the alternatives: (1) add 1 1/2 inches over the existing landing using one layer of ply plus the flooring and adjust stairs; (2) remove top layer of OSB/add one layer of ply and flooring OR (3) remove both layers of OSB/add 2 layers of ply and flooring. At least, I think those are my choices. Any other ideas?