How confident/relaxed are you about not having any firm booking & finding places to stay on the hoof?
You could plan a firm destination each day with a hotel pre-booked
or
Plan a firm destination each day and then look for accommodation once you're there
or
Ride untli about 4pm, then decide to start looking for accommodation.
More importantly, how relaxed will the other half be if it's 8pm and you haven't found somewhere, or have found the only place in town and it's a shitehole
4 blokes on tour won't really care and will find the nearest bar. Your wife may be of the same vein, or she may decide she wants a bit of comfort, etc.
Maybe do a bit of internet research of the rough areas you intend to visit and see what accommodation is around (and if they have a natty website, general availablility of rooms)
Did a tour of the alpine passes in 2006 with a mate. We planned the next days ride over a beer and a map the night before and when it got to about 4pm, either found the local tourist office, rode round the town looking for anything that took our fancy & also hit "hotels" on the gps and checked them out.
How much do you want to spend on hotels/b&b is another factor? Coupla days we got it wrong and ended up in Ibis style ones - we'd tried to use French Youth Hostels, as the one in Arras is great. Sadly, a lot of the rest ain't - one wanted us out by 6am
- that was an Ibis night
If there's a tourist info in any town you go to, they're always good for info on decent, reasonably priced places to stay - we even found a great B&B in Switzerland that put out bikes in their garage and had a view over Lake Neuchatel
Have you a rough route in mind? Put it up and ask peoples recommendations if they've stayed in that area. Then you can do your own thing and you've got possibles if it all goes a bit pear-shaped.
Jon