Visiting the surrounding vinyards at Regua is one of the main sights of this region as this is the very heart of the portwine production.
Quinta da Pacheca is one of the best and easiest places to do it as it is located just a couple of kilometers from the town of Regua and it's a 5 minute drive from town or you can even walk to the quinta.
The place is one of the main grape producers for the portwine house Sandeman and it's a really pretty estate.
Thye have a shop at the quinta too where you can purchase their wine and a few other Douro related products.
They also have a little hotel and a restaurant there, but you should reserve that in advance as it is very popular and often full.
Guided tours of the estate is possible too but should also be reserved in advance.
When I was in Regua – November 2009 – I came across a wonderful exhibition of ceramics and caricatures (sometimes the two categories overlapped) in the public library. Much more interesting than I’d expected. The trompe l’oeil pieces, often with shellfish and insects crawling over plates, etc, were AMAZING. I don’t know how long it is/was meant to go on, but it was in the Museu do Douro and if the exhibition has now moved somewhere else they should know where.