National parks

Hello.

My girlfriend and I are looking into visiting a couple of the national parks in North West Thailand, specifically Sai Yok and Erawan.

We will be looking to visit in around 2 weeks time.

We're just trying to work out how to get there and where is best to stay for a few days to make the most of being in this area.

Questions are:

1. Would it be best to stay in Kanchanaburi. I see we can get the train there from Bangkok. I can also see that the train runs a bit closer to where the parks meet. Would it be better to get closer?

2. If anyone has stayed in Kanchanaburi, is it easy to get transport to the parks as we don't have international drivers licenses.

3. Any suggestions on how long to stay to see a good ammount of both parks?

Thanks in advance!