Also keep in mind that what is perfect for one person is not perfect for another, and we change from day to day. Some days we have energy to do a bunch of stuff, other days we just want to take it easy.
I think the most important part of successful travelling with a partner is to be considerate of each others: Pay attention to what the other person wants, perhaps especially if they need a little break. This does not align well with planning everything in detail. You have to be able to improvise, and to take into account each others needs throughout the travels. :)