Our stop in Riga was a short stay, you can walk 15 minutes from the port or get a free shuttle bus. The town was quite upon our arrival, but slowly becoming alive before lunch time. You can easily walk around Riga on you own.
The Port is about 20 minute walk or catch a free shuttle bus to the centre of Tallinn. A easy place to do on your own, plenty of bars and restaurant's. The town as a market in the centre square and plenty of historical interest.