I venture that Estonia is largely unknown in the U.S., where I'm from, yet the country stands out among her neighbors even in this regard. Technically the country is very young, having last gained independence in 1991 and yet the distinct Estonian culture is centuries old. What happened over the centuries to get to this point is a fascinating history and as you might expect the best way to understand what I'm talking about is to see, breath, and experience Estonia first hand. My wife is Estonian on her paternal grand father's side so that was the impetus for visiting the first time but in the end it didn't matter we keep coming back. In a country that poses a language barrier, learning as much as you can in a short period must be mitigated with a greater volume of exposure and that in turn is facilitated by pursuing mobility. In short: rent a car .
If you're American, you'll need three things at minimum to rent a vehicle:
*a valid U.S. drivers license
*a credit card (debit cards won't fly)
*an International Driving Permit
The International Driving Permit, or IDP, requires you to plan ahead of time by about a month. See here all the information you need to get your IDP: http://www.aaa.com/vacation/idpf.html
With an IDP in hand, next you'll need a car. There are two rental companies that I've noticed are common, these are Sixt, and Europcar though Hertz is also about. I have, along with friends, used Sixt car rental in Tallinn to rent about half a dozen vehicles. I've also used Europcar while on the island of Saaremaa. I've never used Hertz here but I've just booked a car with them at the time of writing this so I'll be sure to share my experience on that at another time. I've never had any trouble at all with Europcar: when I chose them I received a vehicle and service that was as expected and I leased a car within an hour of just dropping in to see if they had anything. Sixt has also provided me with generally good service, especially in the form of a good attitude when they delivered cars to a non-airport location or when a staff member assisted me in obtaining several vehicles for a single reservation at the airport. On two occasions however, I've been shocked at how poorly the Sixt staff in Tallinn can behave. The first problem event was the day after my wedding in Tallinn. I was told I would likely need to pay for fees associated with a computer system problem that immobilized the vehicle I rented. I was stern, but respectful, in disagreeing with the staff about liability for problems with their equipment. In the end I was not charged. All the same, arguing an unfair bill is the last thing you want the day after your wedding. The second problem I had with Sixt in Tallinn was on Christmas eve. I wanted to pick my wife up from the ferry terminal where she would be arriving from Helsinki. I wanted to start our Christmas eve right after being apart for a month and pick her up with our own car. Sixt confirmed my reservation with no stated restrictions around timing for the reservation. At my scheduled pickup time, I waited in the parking lot for a car. Over half an hour after my expected delivery I received a message that said my reservation was canceled, without explanation. After several calls to Sixt I finally got through and spoke with a rep at the airport office. She explained the cancellation saying, "...we are not like Germany where 2 hours ahead you can reserve a car..." which I found particularly shameful. Europcar, in contrast, places restrictions on internet booking: they won't even let you book a car online within a 48 hour period as they state explicitly that they can't do it. The lesson is that if you want German transparency, and German service from a German company in Estonia, it is paradoxically not Sixt in Tallinn that you're looking for, per the words of their employee at the Tallinn airport. So I suggest Europcar but either way be sure to enjoy the freedom of driving while you are in Estonia.