@ Charlie D,
I believe that you and your Mrs. shall have an unforgettable epicurean escape and an amazing visual production just on foot !
My suggestion is that you do careful research and speak to colleagues, siblings and / or friends who have travelled in Europe. Do not bite off too many places in 1 trip. Select 1 country and 1 other close by. For example: Italy & Switzerland or Italy & France or Spain & Portugal or Spain & France. This way, you do not waste time travelling long distances. There is so much to see in just 1 country.
Monasteries, castles reformed and now hotels, architecture, a winery with a hotel and wine tasting course, Urban culture and a couple of days in the mountains at a Rural Inn and / or at a lovely seaside port town with fresh shellfish right from the sea. www.parador.com
( Spainīs Hotel Parador Network of 93 Hotels, 50% of them in historic buildings - the website is trilingual, English. Spanish and French.
In Italia, well, this is enchantment, A to Z, I recommend VENICIA ... This is a city, that enchants, and there is only one !