Well, sometimes the hotels are different for each tour.
Bourges - I stayed at the Best Western Hotel d'Angleterre and I'm pretty sure the bus got right there to the front.
Amboise - I think it was Hotel Belleview. Bus up to the front
MSM - Yes, this is a trek. The bus parks in a lot. You take a shuttle across the causeway to near the entrance of MSM. You then walk up the main street and depending on where your room is located, you may need to continue up that street with your suitcase, maybe up a flight of stairs and continue up a bit.
Bayeux - I think the bus dropped off right in front. I also think I remember that we needed to walk across the road with our suitcases to the parking lot when we were ready to leave.
For MSM, you are only there 1 night. I recommend taking in a small day pack with limited toiletries, a clean shirt and unders and night wear. Leave your suitcase in the luggage bay of the bus so you don't have to fool with it. I used my "bus bag" - small day pack I had on the bus with a jacket, guidebook, electronics, snacks. I put my clothing in a packing cube, popped it into the day bag and just used that to go out to MSM. You can re-pack in Bayeux. My hotel room there was huge, lol!