We went there near the end of December.
It takes two whole days because the first day is for visiting the palace and the second day is for visiting the gardens. We did airbnb near Versailles because going back and forth to Paris takes so much time and it exhausts your energy sitting in the train.
Ok, so there are two waiting lines and two check points before enter the palace. There is a waiting line and a checkpoint before you enter the gate.
After that, there is an even longer waiting line before the second checkpoint which is in the palace. Get your breakfast while waiting in line because it took us 3 hours of waiting before we can finally explore the palace.
So waiting in line takes up quite a lot of time and you probably get tired of walking and go home before it gets very late. That's pretty much a whole day gone just for visiting the palace.
For the second day, we didn't have to go through the second waiting line and checkpoint because we were visiting the gardens which do not require tickets. The gardens are quite huge. There are even small palaces in the gardens, but these small palaces do require tickets. Each garden has its unique setting and are far apart from each other. That takes a lot of walking, you'll be even more tired than walking around the palace for sure.
It is worth taking two days to explore Versailles even if you are like me who just wants to take a picture, read some stuff, done, next stop. There is just so much stuff to see and read!
O yeah, here are some tips: Dress very warm because it was very cold in December. I had two jackets on and I was still freezing while walking around the gardens.
The bathrooms throughout the palace and gardens are free, so don't worry about your bladder. If you are a student under 26 studying in Europe then you don't have to buy any tickets if you show them your Id. If you do not qualify and need to buy a ticket, please buy it online, otherwise you'll have to stand in another line for a ticket which is outside the gates, that will save you a whole waiting line!
It was overall a fun and meaningful experience!