Sorry for the limited info...
We are looking at 2 weeks. We are not big eaters. We enjoy sit down dinners but can grab something quick for breakfast and lunch.
We really don't want to stay in large Hotels but rather smaller B&B type places. We want to get out and see the country and meet the people.
It would just be 3 of us...
If you are serious about that last point, like a PP, I would encourage you to narrow the list to two countries and one or two "home bases" in each of those, so you can have time to do more than hit the major tourist highlights.
If it were my friend, my personal recommendation to someone wanting to see a fair amount of variety and things everyone has heard of but also have time to get to know people and have a more local feel would be to narrow it to Germany and Italy and do the following:
Fly into Frankfurt (I would start with Germany to lessen "jet lag" Both countries are on the same time zone, but Germans tend to eat dinner at 6 or 7 and whereas Italian places normally do not even open for dinner until 8:30 or 9:00---so it feels like a longer time gap than it is).
From Frankfurt, take the train (45 minutes) to Heidelberg. Stay 2 to 3 nights in Heidelberg and explore the city and nearby small towns (Schwetzingen Palace, Bad Wimpfen) while you get over jet lag and get settled into the culture a little.
Take the train to Munich (3 - 4 hours depending on type of train and connection). Stay 4 to 5 nights in a guest house (smaller hotels, privately owned and generally owners run them themselves and are very sociable with guests) and explore Munich and take day trips to other nearby areas that interest you.
Fly from Munich to Milan (Duetsche Bahn has actively discouraged us from taking trains to Italy several times. They don't work well with Italy, or Spain, and things get very pricey and take a long time). Short flights with in Europe can usually be had for 100 Euro or less even on major carriers if you keep an eye out and are a bit flexible on dates or time.
Spend an afternoon in Milan and then take a train to a B&B near Florence. Spend 3 or 4 days there and exploring Tuscany.
Take the train down to Rome and finish up with 3 or 4 days there (note: I really dislike Rome and that is where
I always feel like they are trying to gouge tourists, but I know most people love it and most want to see it).
Fly home from Rome.
Guessing prices, for the parts in Germany (I am less familiar with Italy--we tend to go their on cruises or else rent a house):
About 1300 euro in food and hotel for a week staying in triple rooms in locally owned guest houses and 400 in longer trains in Germany (25 from the airport to Heidelberg and 100 to Munich, if ought ahead on the db.de website). Maybe another 700 Eurosin entertainment and local buses and trams (which I think is guessing VERY high, but not knowing what you like to do) for pricing for the one week, if that helps.
We are in london right now. It was almost 7k for three RT tickets on British Airways from houston to london. The hotel is going to run 3k for 7 nights. Meals have been very expensive, basically double what we are used to. They definitely gouge tourists over here. Luckily we did club level at the hotel so breakfast, snacks and drinks are included all day. We only eat out for dinner.
I agree with a PP that the main issue in London is that the Pound is so strong. It is an expensive city, but no more so than New York or Paris or any other major city that both locals and tourists love. Locals seem to be paying the same rates (unlike in Rome!).
If you see this and are getting sick of bleeding money:
We like to pick up the picnic package at Tesco's and take it to a park for lunch. Last time I was there, those ran 4 pounds for a choice of sandwich, side dish (chips, baby carrots, etc), choice of bottled drink and a a choice of dessert (candy bars and cookies and the like).
There are also a couple of fairly casual chains that had better prices and were good food, in our opinion. I really like Nandos Chicken (bonus--free drink refills!) and Wagamama's Asian food.