Europe's most scenic train ride is the Glacier Express across southern Switzerland. The most scenic boat ride is from Stockholm to Helsinki — countless islands and blondes. Europe's most underrated sight is Rome's ancient seaport, Ostia Antica, and its most misunderstood wine is Portugal's vinho verde (green wine).
Honeymooners should try these tiny towns: Beilstein on Germany's Mosel River; Hallstatt on Austria's Lake Hallstatt; Varenna on Italy's Lake Como; Ærøskøbing on an island in south Denmark; and Gimmelwald, high in the Swiss Alps.
The most pleasing French château is Vaux-le-Vicomte, near Paris. The best Gothic interior is found in Paris' Sainte-Chapelle church. The top two medieval castle interiors are Germany's Burg Eltz on the Mosel River, and northern Italy's Reifenstein. Lisbon, Oslo, Stockholm, Brussels, and Budapest are Europe's most underrated big cities.
I'll close with a lightning round of "ultimates" (what travel writer can resist?): the ultimate medieval walled town in Germany (Rothenburg), prehistoric stone fortress in Ireland (Dún Aenghus), Riviera port town (Vernazza), hike in England's Lake District (Catbells above Keswick), neighborhood pub in London (The Anglesea Arms), castle in North Wales (nope, I still can't pick just one)...and pedestrian market street in Paris (Rue Cler).
Having stuck my neck out to say all this, I must add that it's always fun — and necessary — to reassess opinions (mine have certainly changed over the years). These are just my personal feelings after more than 100 months of European travel. As you sort through these "bests" and "worsts," go ahead and disagree. Don't let any travel writer limit your freedom to find your own ultimates.
Rick Steves (www.ricksteves.com) writes European travel guidebooks and hosts travel shows on public television and public radio. Email him at firstname.lastname@example.org and follow his blog on Facebook.