Two great topics going on here... my input (late as it may be)...
There is only a single cocktail who's recipe should include "Rose's", and that one is the "Gimlet". Even for that, I usually prefer to simply use fresh squeezed lime juice and simple syrup, not only does it taste better, but since there is no other reason to have Rose's around, it's far more practical.
In it's day, Rose's was a sort of welcomed addition to the cupboard. Back then fresh limes were harder to find, and so a sturdy bottle of Rose's that would keep well was often better then nothing at all.
But as a "quality" cocktail mixer it really can't compare to the real thing. Nothing grieves me more (ok, a few things) then seeing a bartender use Rose's in a cocktail that normally would have used just fresh lime juice (ie. not even any added sugar). Far too often folks treat Rose's as a substitute for fresh lime juice, even though that is not it's purpose at all.
If you see a recipe that calls for Rose's, do a little more research and see if you can fine versions of this drink that call for fresh lime juice and see if they "also" call for sugar or not. This should help you understand how to make this drink in a more quality minded manner.
As it has been stated by a few already... yes, a "properly" (as in like it was originally) made Martini includes orange bitters. When making them at home, I virtually always include this. And when I happen to drink them when I am out, I almost always have a little vial of home-made orange bitters with me that I can add to my Martini. And when I am out, I will order my Martini "extra wet", which unfortunately is how I need to let the bartender know how to make this so that it has enough dry vermouth in it to actually provide a better "balance" of flavors then how they normally make it.
Originally, virtually any drink in the "Cocktail" category included bitters in one form or another. Back then, there were dozens of different types, and many bartenders even had their own private recipe that they would make up themselves.
As for Peychaud bitters in a Martini...
I recently worked up a special food and cocktail pairing for a restaurant in New Orleans (to be featured at the upcoming "Tales of the Cocktail
" event), and for one particular dish I selected a Martini style cocktail (and I mean that in the true sense of the word, and not just a drink served in a "Martini" glass :-) that used Peychaud bitters.
Here is the recipe:Tillicum
2 1/4 ounces gin
3/4 ounces dry vermouth
2 dashes Peychaud's bitters Stir with ice. Strain into a cocktail glass. Garnish with a slice of smoked salmon skewered flat on a pick.
The skewered wafer of smoked salmon is remenicent of the way the Pacific Northwest Indians would cook their salmon
around the lodge fires, and so I named it "Tillicum" in their honor. The Peychaud bitters adds a nice "salmon pink" color to the drink.