The train segment from Tambo to Ollanta and back is really slow. While it's convenient to have the train station next to the hotel, for some reason it takes close to an hour and a half to go the short distance. I suggest a taxi to Ollanta and back and the train from there, could save as much as 2 hours of transit time.

We went twice in mid October and both days it was quite cloudy and raining early in the morning and we weren't able to see anything till later in the day. Additionally, most people have the same idea about getting there super early to beat the crowds from Cuzco, but I found the late afternoon to be far less crowded after the early birds headed back down the hill.

It's possible to do a day trip from Tambo without spending the night in Aquas Calientes. It's a long day especially if you catch one of the earlier trains from Ollanta. But worth it to have the hot tubs waiting for you and not having to pack/ unpack your stuff several times.

Hope this helps.