I walked in OTR the other day and saw a lot of construction going on.  The new windows looks great everywhere !  Who are the vendors that supply those ?  Any advice is appreciated...

You would probably have to contact the developer or general contractor.

Look closely at the ones you like the most and look at the label.  There are several big manufacturers (ie Marvin), that make windows that are somewhat historic. 

 

You can also get custom made sash to fit in existing frames with the ropes and weights etc.  This is a lot of work, but you end up with a much more authentic look in the end, and they can be fitted with an interior storm by Allied Window for an excellent overall look.  I have rehabbed and installed lots of sash.  There are several local carpenters who can make them at reasonable cost.

^That's interesting.  I've never seen an interior storm window before.  I put exterior storm windows on my house (albeit not in OTR) after reglazing and rehanging the original windows, and they look great.  Most people don't even realize that the storm windows exist from the street. 

Well there are the cheap, triple-track exterior storms that look like crap, and then there are the single track exterior storms that are almost invisible.  A local company, Allied Window are experts in both of these and have done many interior and exterior storms all over this region on historic buildings.  The interior storms are fantastic if you want a really historic exterior.  They are held on with magnets on and are almost invisible.

Any photos?

Magnetic storms are the way to go. But if you keep your windows properly glazed, painted and weatherstripped they work remarkably well.

 

My biggest gripe about our house was it came with replacement windows Installed by a previous misguided ownerand now I have to built 16 new "old" wood windows.