Best Plan for Cusco to Machu Picchu

I will admit I did this on a tour. It was in April after major flooding, so the train was running 'light' as the rails had been washed out and replaced and just opened 3 days before. Water was still rushing down the river through 'Machu Picchu town' and the town looked like a construction zone. Our hotel room hung over the river....literally. There was a space between the wall and floor where we could see the raging river below. It did not leave a good impression of the town- but I would recommend you stay there a night or two to allow for the earliest arrival to MP that you can manage. It has been a while, but there was a bus shuttle from the centre of town to the entrance. I believe the first one leaves before daylight. If you want to be at the sunrise point for that, then you need to be in town.
Depending when in December you will be there, you may be there for the rainy season - which means low hanging clouds and fog. Even in April, weather may reduce the visibility in MP. We arrived a day before our scheduled visit due to the train situation. Thursday afternoon was sunny and dry. However, the Friday morning that we were supposed to visit, one couple went up for a second visit and fog was so thick you couldn't see 10 feet ahead of you. Total white out. So another reason to stay in MP town is to book 2 visits to improve your chances. Despite it being rainy season in December, it is also one of the 2 busiest months for tourism, so book ahead.
I was fascinated by the Moray Circles (terraces) in the area. It doesn't look like much, and I would recommend taking day tours or short multi day tours to get a better understanding of their uses as micro climate testing spot, and the other features of the valley.
There are also salt pans (I didn't see them, but DS did) which are interesting.

The sites and town of Ollantaytambo are interesting. The ability to cut massive blocks of stone and have them fit together perfectly is best seen here. The town is more traditional with gutters, cobblestone locals in traditional dress.
Chincero site offers amazing views and a very peaceful ambience.
There are a good number of sites to see, so again, read ahead to decide which ones are of most interest.
Particularly in green season, the Valley is lovely. I expect that self drive would not be difficult; but do invest in a good guide book if do decide to do it totally DIY.

I just read a news article that Machu Picchu has just reopened, at reduced (30%) capacity, after a 9 month closure for the COVID virus. The article did not mention reservations, but I assume you would have to make them a long time in advance as the tour companies will gobble them up quickly.

We did a four day tour of Cusco, the Sacred Valley and Machu Picchu in late March 2019.
The tour was with PeruAgency.com
Except for the first tour of Cusco we had a private guide for the entire trip. Cost including hotels was $799 pp.

The tour included many ancient sites around Cusco, the key sites in Cusco, also a day on our own in that city, several more ancient sites in the sacred valley and a scenic train with glass roof the final part of the trip to Agua Calientes, near MP.

On the site of MP itself, we had a wonderful guide, who had a University Degree and was very well informed. We started the tour at 6:15 and finished about 1PM. We are in our early 70s, but active. The altitude and all the hiking up hills was a bit tiring, but it was so exciting and wonderful, we did very well.

After lunch, we took the same scenic train back part of the way to Cusco, then a bus, then we were picked up by our original guide for another night in Cusco.

I was a bit apprehensive about going during the rainy season which doesn't end until the end of March. However, we had no rain while on tour. We had to do the tour then, since we had to pick up a cruise in Chile that would take us back to the USA.

We met people on our Celebrity Eclipse cruise ship that had take Celebrity's excursion to MP for $3000 and it wasn't as nice as our tour for $799 as well as airfare Lima-Cusco-Lima for less than $200.

I didn't list all the sites that we visited on the tour. Here is my review of our trip as well as the cruise afterwards.
Cusco, Sacred Valley, Machu Picchu and Celebrity Eclipse home
https://www.cruisecritic.com/memberreviews/memberreview.cfm?EntryID=654963&et_cid=3214772&et_rid=17221689&et_referrer=Boards

You should understand that approaching Machu Picchu is not like getting to other tourist places - including, say, Ankor, Cambodia. There is no real highway to Aguas Calientes. This requires planning, and advance commitment of money. In time of Covid-19 restrictions, there is a danger that travel insurance will not pay out for possible cancellations.

We went on an organized tour with about 20 guests. I chose the tour specifically because it included the VERY expensive, TINY hotel at the top of the mountain. But there are small number of Superior Tourist Class hotels in Aguas. But you have to wait in line for the jammed public bus, when the serpentine road opens in the early morning. (Often, fogged in.)

Despite the hotel location, our two sunrises were fogged in, but we did get some sunsets at Machu Picchu, with the other tourists already gone, on the "last bus." I'm not telling you there is only one way to do this, but just suggesting that you have realistic expectations about your options.

We did that as part of our National Geographic tour. After flying to Cusco from Lima we took a bus to Urubamba where we stayed at Sol y Luna. En route we stopped at Pisac to see the ruins. After a night in Urubamba we took the bus to Ollantaytambo where we spent a few hours walking around the ruins prior to taking the train to Machu Picchu town/Aguas Calientes. We took a bus up to the Machu Picchu site where we stayed at Sanctuary Lodge right outside the ruins. On the return, we spent one night in Cusco. We visited Saqsaywamam and stayed at El Monasterio Hotel a couple blocks from the main plaza. Finally, if you enjoy climbing, once you know the specific date you will be visiting MP, sign up to climb Waynapicchu at MP. When I was there you could just show up in the morning when 175 or so people were allowed to climb. I’ve been told you need to sign up beforehand now.

KBK,

Are you planning to travel to Peru this December (ie: in about three weeks)? Hopefully you don't have any Covid-related travel issues.

If you haven't already, you may want to read this U.S. government website, especially related to Dengue Fever - https://pe.usembassy.gov/covid-19-information/ .\

Hi Ken: We're scheduled to depart in mid-December for 9 days. Appreciate you sending the link! Our fingers are crossed things will go smoothly. Thanks again!!!

Thanks for the feedback everyone. Have decided to postpone until May due to COVID uptick/uncertainties.

Good plan. Good luck and hope for brighter outlooks for you and May visit.