I would use a quality vinyl, like an Okna, Softlite, Polaris. Don't use the cheap box-store crap whatever you do.

WOOD!!!! Please keep the character of the house alive...

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Wood framed windows are a never ending upkeep they need painting all the time I think you can keep the look of the originals but with vinyl or aluminum clad and keep the upkeep to a minimum and who wants the hassle of storm windows not to mention how bad old windows are for leaking heat even with weather stripping.

Since worrying about authenticity did not enter into the original question IMO that was not an issue. Not all of us care about keeping old stuff that does not function just because it is old.

Not only that this is said to be a vacation rental. Why would you want to spend what for most of us is limited vacation time maintaining wood windows. I am the biggest proponent of wood windows but vinyl has its place as well.

The posts above have outlined the trade offs, it's up to you to decide what is most important to you.

I regret that we did not look into repairing the double hung windows at the front of our home. The vinyl replacements are just OK. I didn't realize at the time that double hung windows could be fixed to slide more easily etc.

The house is charming.

So much great input! Your first step should be finding out if you can repair your windows as opposed to replacing them. My credentials: I'm originally from Maine (we're all about real, authentic, preservation, etc.), now in NC, and I've got a charming older home that needs new windows. We will NOT replace my wood windows with vinyl ones. We will replace or repair them, a couple at a time, until the job is done. Wood is very expensive. However, your house is in a fairly harsh climate and it's a rental property. Go for the vinyl. Get good quality from a highly recommended vendor who has done business in your area for a long time. Do NOT get the mullions that are permanently in between the glass. A well maintained, snug, warm, low maintenance home is your goal.

Thank you all for your advice!

Look at a metal clad wood window like Eagle (Anderson E series now) Granted old windows were made from nice VG fir but their days are probably over and you will never get the same energy efficiency as a new window. Older is not always better and I'm glad we "don't build them like they used to" With a metal clad window you get the warmth and beauty of a wood interior with the durability of a painted metal exterior which eliminates any maintenance.

I vote wood for all the reasons above. Vinyl is the worst, and they do require maintenance when the seals break and they warp. Except you can't maintain vinyl; you have to replace. I would rather repaint wood windows every 20 years than replace vinyl every 20.