Negotiating hotel and B+B tariffs?

Quite simply, you don't negotiate. The quoted price is the price you're expected to pay.

For the most part I have to agree with Tom but asking if there is a discount for multiple nights is reasonable. I would also book directly with the hotel/B&B - that saves the hotel any possible booking fee they may have to pay a third party agent and some will also pass this savings on to the guest. You can also inquire if there is a discount for paying cash - some also do that.

We are "book as you go" travelers as well but I usually book the night before we leave our current place for the new place - that way I can do a little research online, read the reviews of a place and compare pricing. That way also saves the time spent stopping at two or three different places and we have a place as soon as we arrive in our new destination to stop and leave the bags.

We always try and stay very near the train station - I usually pull up the google map of a place and zoom in to the train station - then I can see what hotels/B&B's are close - I then check those out on sites like Trip Advisor & Booking.com but then book directly with the hotel either using their online booking or sending an email.

One extra thing you should probably know about is Kurtaxe - this is a special local tax which towns with a level of tourism disproportionate to their economy are allowed to charge tourists to support municipal services. It is usually somewhere between 2 and 10 Euros per night and is collected by the hotel when you check in, separately to the accomodation bill.

Just to be clear as tourists sometimes react badly to this - it's an accepted part of the German tax system and not any kind of scam. Some towns offer discounts for transport, attractions, and restaurants to people who have proof of payment (so don't buy any kind of local transport pass before you've checked into your hotel, just in case your Kurtaxe gets you one free or more cheaply).

Plan to pay the established rate. The only exception that I've ever heard anyone mention is requesting a discount for cash. I've never tried that, because I feel like the prices I am paying are fair. Also, many small places, like the ones I stay at, require payment in cash.

Regarding booking rooms at the last minute... I always book all my accommodations a few months before I leave on the trip because I want to stay in low-cost properties that are well rated, are centrally located, and are en suite with an elevator. Those types of places are usually booked ahead of time during high season, and September is still high season in most of Europe. I also don't want to spend vacation time searching for lodging.

However, if you are really flexible about the type of lodging, its location and amenities. and its cost, you could certainly preserve your freedom and book a day or two ahead. The tourist office would be a good place to start looking for room.

If Rick's guidebook listing for a hotel says "discount for cash," or with book, or for 3+ nights, etc., do ask for those, since they may assume you will pay with credit card or don't have the book. Some will only take cash, anyway. I certainly have just rolled up to a tourist office (note typical opening hours) to get a B&B referral and that is easier if you are flexible on price or location (e.g., you have a car to get to a more rural spot). But calling or booking online a day ahead (direct with each property) is easier now than ever. Of course, you can call more than one for a price/availability quote before deciding.