Some background -- Wife and I live in Florida, USA -- Both recently retired. In our early 60's, reasonably healthy/fit. Have traveled to Ireland every year since 1999. Have also made brief visits to Cotswold's (4 days), Amsterdam (3 days), Edinburgh (3 days), Paris (2 days), Bruges (2 days) and Brussels (1 day). Have traveled via train in Ireland, Scotland, Wales, Paris to Bruges (Thalys) and in Belgium. Wife is 'Iffy' about the Eurostar, though, as she has 'Tunnel' issues -- even in cars. Not opposed to occasionally renting a car for SOME of the trip -- if appropriate.

Have been thinking about flying into Europe and 'Sampling' major destinations by train. Looking for route, itinerary and time table ideas/suggestions/advice: i.e., "Fly into Hamburg, spend 2 days, train to ... ???"
Will also be incorporating 4-6 day visit to Ireland, so flight will Definitely be Open-Jaw / Multi-City.
Have NO set preconceptions -- Include Denmark/Norway/Sweden? Spain?
I'm thinking of 20+ days -- ON THE GROUND -- Budget of $&-10,000 -ish.
Am thinking Vienna, Venice, Rome, Turin, Switzerland, Berlin and Budapest are likely candidates. Don't expect to see EVERYTHING -- looking for a 'Check The Box' SAMPLING, to get a feel as to what 'Grabs' me, once I'm there -- if that makes sense???

Appreciate any and all help.

Bob