Thanks to everyone for their thoughts. Looks like taxi it is. I had a hunch that a car of sorts was going to be the easiest option, but I just wanted to compare the taxi fare vs the hotel offering.

In answers to other questions, it's the weight of the luggage which will present the problem to my partner. Once we pick up our lease car, then it shouldn't be a problem as I will be able to do the lugging from car to accommodation. Stairs without luggage should be doable as it wasn't a problem last time we were in Paris. We are intending on doing a fair bit of walking.

We emerge from Europe at Frankfurt, about 8.5 weeks after our arrival.

Looking forward to the trip. Still a lot of planning to do, but that's half the fun of travelling!

Cheers!