Cafe Britt actually offers 5 different tours including combination tours that can be done with other destinations such as the Butterfly Farm, the Aerial Tram and the National Theater. Those may be a good deals for you if you are interested in seeing those things too. Here is the official site
http://coffeetour.com/home.htm which does not list prices for some reason. Another link provides greater detail
http://www.centralamerica.com/cr/tours/cafebritt.htm. This final site lists the basic tour at only $20 but may not have been updated recently
http://www.costaricatours.com/oneday/oneday07.html.
Yet another coffee producer altogether is the less commonly known but award winning Doka Estate, which is the bulk supplier to Starbucks for Costa Rica. A tour of their planation and facilities is usually included on the all-in one-day tour, which also hits Poas Volcano, La Paz Waterfall and Braulio Carillo Park for $75/pp and returns to SJ by 5PM.
I have been on both and they each have their special appeal. The Britts tour is almost a rite of passage for all CR visitors. The quite hokey yet entertaining skit is worth the price of admission. Of the combo destinations with the Britts tour. The Butterfly Farm is interesting and educational, but if you just want to see pretty butterflies go to the Mariposa Gallery in the National Museum. BTW, the National Museum is another must-see and can be done at your leisure any day except Mondays ($1 admission) as it is only a few blocks from the Gulch. In addition to the butterflies, it has historical displays and various other sections that are all very interesting and educational. Allow at least a couple of hours. Try to time your visit so you get out when they close and can then check out the chica secretaries as they get off from work at the neighboring government ministries. Also check out the crafts market in the nearby Plaza Del Democracia on the way to or from the Museum.
The Aerial Tram may be a better bet as a combo tour as that destination can not be easily seen except as part of a package tour. Lastly, if you do not go on the Doka combo tour, try to get on some other tour that takes you to the La Paz Waterfall Park as it is quite beautiful with a whole series of waterfalls, hummingbird garden, butterfly gallery and jungle trails.
As to volcanos, of those mentioned only Irazu and Poas can be driven to the top. Arenal would probably be out as a day trip since it takes 3+ hours just to get there. But it does make an excellent overnight, particularly when combined with a visit to the Tabacon Hot Springs. It is also the only currently active volcano. Barva is the most dormant and least accessible of the others, although I did take a nice horseback riding trip along its slopes once. Poas has the most to see and could be combined with a visit to Britt. Irazu, does not have much in the way of facilities or trails. It erupted last on the day JFK was visiting CR. A tour to Irazu is often combined with visits to Cartago and the Orosi Valley. It is said that the summit of Irazu is the only location in the Americas where one can see the Atlantic and the Pacific at the same place, though it has always been too cloudy for me to see it whenever I have visited. It is important to get to these volcanos as early as possible for the best views as they cloud in early. That is why it might be worth your while to hire a driver to take you to these places ahead of the crowd of tour buses, which arrive a little later after picking everyone up.
With the exception of the Arenal tour and possibly the 4-in-1 highlights tour, all of these tours will take much closer to 6 than to 12 hours. Which volcano you choose to see will depend on what else you want to see with it and how much time you have in CR. If you have more than a few days why not see both Irazu and Poas, or better yet find a chica and take her to Arenal/Tabacon. After a hot soak and a romantic dinner with the glowing lava covered volcano as a back drop, she will be putty in your hands and the volcano will not be the only thing to erupt that night.