what is the generally accepted age to get discounts for seniors? We will be in Germany, France, Norway, Denmark.
It may depend on the discount you are expecting to get. Museums and other entrance fees generally vary by country and venue, but I recall them to be more like 60 than 55. I do not think that "Senior" discounts for hotels or meals are all that common, if at all available.
Actually, Best Western has a seniors' rate which I believe has age 60. I know we got it when we were in Salzburg adn when you go to their website you declare your age and get the discount.
Some senior rates are only available to EU passport holders.
In Germany some hotels/attractions etc. grant senior citizens discount from the age of 60, some others to anybody holding a retirement card/pension card. The word to look for on the rates list is "Rentner". If you are retired bring a certificate or anything that proves you're officially retired (you're a Rentner).
After 20 years of travel I don't ask about the age limit; I ask for a senior ticket. Let the agent ask how old you are if he chooses. Many don't; they give you a ticket. Some places its called pensioner fare.