I believe the look will be one of a kind and great. The whitewash would certainly brighten the room but wherther that's needed or desired hinges on several things. Personal preferance takes president over all the others. Higher a ceiling,less important for light color. Ample natural and artificial light alows for darker colors,esp ceilings. You are correct about polyurathane making future painting more problimatic. You don't need the durability of poly anyhow so there is no reason for useing it. Regardless what you do,spraying is the only way because there is no way under the sun of getting paint in all those cracks,saw marks,splits and fissures with roller and brush. So if you don't own a sprayer,I suggest you buy a HVLP rig and begain pratice. If you already know how you could of course rent one. Were it mine I would use non-tinted acyrlic latex tint base. Easy to apply,easy to clean up,no foul odors while painting and can be painted over without special prep. There's one potential downside to water clean up paint. Tannin bleed from the wood. There are a few options for working around bleeding,should it occure. Coat it first with shellac. Recoating acyrilic with tinted aycrilic. Tint has many options within it's self. Tinted to color as origionally manufactured for. Slightly tinted but still some transparancy. Slightly tinted in 2 or more pastel colors and appyed in an iridescent pattern making the bled color part of the schem.
I hope youall are useing breathing,eye and skin protection.There is little doubt the material you are ripping out includes lead and asbestos.

Every body in my family likes the look of the scraped floorboards and agrees they shouldn't be painted over.

What do you think about Peel Stop Clear? Someone suggested it on another thread, and I was thinking it might be a good choice, since it could be painted over later.

Would the non-tinted acyrlic latex tint base dry clear or white?

"I hope youall are useing breathing,eye and skin protection.There is little doubt the material you are ripping out includes lead and asbestos"

Well, I am but no there is no lead in this paint I am scraping. It was just lime and water.

We might have gotten lucky with this house. All the original lime washed surfaces were covered up with drywall/wallpaper and cheap paneling. Then an addition was built int he early 1980's after lead paint was banned.

"Personal preferance takes president over all the others."

I disagree. Respect for the history of the building takes precedence over the whims of the present stewards. These buildings live much longer than we do. With few exceptions anything done should be reversible.

My biggest concern is that once I poly, it will be difficult to paint over in the future.

No, it won't. Although a clear alcohol-based shellac would be easier for future restorers (if any) because it releases easily with paint removers.

If you like the looks of the semi-cleaned beams and boards, a clear coat of something to keep chips of whitewash from landing in your coffee would be a good idea.

A sprayed coating would give you best coverage.

Lime plaster and whitewash are REALLY irritating to skin ... not toxic like lead, but nasty low pH and dust that dries your skin and makes it itch.

After getting advice in the Painting forum, I am going with Peel Bond primer. It goes on thick like mayo so it goes in the cracks easily, and it dries clear.

I painted two of the boards to test it. When I came back the next day, I could not tell the difference between the ones I painted by looking at them. I had to run my hand across them to figure it out. While the painted ones were not smooth, no dust fell like it does if I run my hand across an uncoated board.

I haven't had any problems with the Lime irritating my skin thankfully. I really hate getting it in my hair. It reminds me of drywall dust. I look really ridiculous. I put a old tshirt over my head to protect my hair, goggles and a mask. Thankfully I am almost done scraping. Just three more sections left, then I can get the whole thing sealed/painted. I didn't get a chance to work on it, as I was distracted by more important projects.

After getting advice in the Painting forum, I am going with Peel Bond primer. It goes on thick like mayo so it goes in the cracks easily, and it dries clear.

I painted two of the boards to test it. When I came back the next day, I could not tell the difference between the ones I painted by looking at them. I had to run my hand across them to figure it out. While the painted ones were not smooth, no dust fell like it does if I run my hand across an uncoated board.

I haven't had any problems with the Lime irritating my skin thankfully. I really hate getting it in my hair. It reminds me of drywall dust. I look really ridiculous. I put a old tshirt over my head to protect my hair, goggles and a mask. Thankfully I am almost done scraping. Just three more sections left, then I can get the whole thing sealed/painted. I didn't get a chance to work on it, as I was distracted by more important projects.