This topic has been thoroughly discussed many times before. Try doing a search next time for ideas. If you need to narrow your search a little, try doing a search of posts just by me in the Non-Gulch section. That will also return a lot but I think you'll find that, while I may not know nearly as much as the true mongering experts on that aspect of CR travel, I do know more than my share about the non-mongering stuff and you can learn from my posts about the various pros and cons of each activity.
Here is one of my posts in particular that lists out at least 33 seperate activities that one can do out of SJ, including many links, and that just scratches the surface.
http://www.costaricaticas.com/phpBB2/viewtopic.php?t=16082&postdays=0&postorder=asc&start=16
IMHO ALL these "day trips are worth it" and you can't go too far wrong with ANY of them. But, if NYCMonger wants to know which are the ones that I think are
MOST worth it, I'll provide my own shortlist:
1) IMHO, a trip to CR is not complete without doing a
w/w raft trip for at least one of your days. As further proof of how much I think of this particular activity, I think it also has great repeat value and can be great fun to do again and again even if you've already done it on a previous trip.
2) I prefer to refer to canopy tours as
Zip-line adventures rather than as real tours of the forest canopy. You're justing flying through to quickly to really appreciate or learn much about the forest canopy. But they can be real adrenaline pumpers. I've done these myself numerous times. I'm not quite as enamored with them as I was at first and so do not rate them as repeat performers quite as highly as I do the rafting trips, but I still rate them very high for those who haven't ever tried them before.
3) A
coffee tour. Doka is more serious. Britt is kinda of hokey but very entertaining. Both are very educational (is that a 4 letter word?) plus if nothing else get you out in the country. But if you really want to spend a relaxed day actually learning something, try the Cafe Britt / Butterfly Farm combination tour.
4)
Volcanos, either Poas and/or Irazu. They each have their unique qualities. If you do either of these, try to get to them as early in the morning as possible (a possible big negative for late night mongerers) and combine them with some other activities. For example, Poas can be easily combined with either a coffee tour and/or a visit to La Paz Waterfall Park. This latter place should probably be listed as a higly rated activity of its own since it also offers some wonderfull butterfly and hummingbird gardens in addition to the wonderful waterfalls. For Irazu, you can also combine a stop at the Cathedral in Cartago, Lankester Gardens and the scenic Orosi Valley.
5) To be honest, I haven't tried it yet myself, but this next one gets such high marks by others I know who have been on it that I'll throw it on my list anyway. The
Isla Tortuga tour not only gets you out of the Gulch but out of the Central Valley and out on the water (on a catamarran in the Gulf of Nicoya) for an entirely different view of CR.
Its hard to pick just 5 and if you ask me on a different day I might include some other tours on this list instead. For example, you may have noted I did not include the 4-in-1 tour. The reason for that is that I think it is better to focus on a few things and do them right rather than rush through a whole bunch, particularly if one figures that they'll be back to CR and have the opportunity on other trips to see the things they may have missed the first time around. However, this could be a worthwhile option if you figure this will probably be your first and only trip to CR. Another justification for some, as Counte Dante already pointed out, is if they only plan to venture out of the Gulch for 1-2 days of their trip, rather than "lose" any more precious days of mongering than they have to, but need to be able to show someone back home that they were doing more innocent activities all that time they were down in CR. If that's your game, you might want to bring a change of shirts so your pic can be taken at different locations dressed differently adding to the illusion that you were there on different days. However such a manuveur probably won't be as easily carried out on a tour with feminazi ecotourist co-participants as it would be if you tried the same scam on a golfing or fishing excursion with a bunch of the guys. At the very least bring a light waterproof windbreaker (which could also come in handy in SJ when it rains) and/or sweatshirt to wear on top of the volcano which can get rather cold and windy. If done right that might also make it less suspicious to any nosy gringa tourists what you're really up to.
Some other clarifications of prior comments made in this thread.
There are actually several companies offering different variations of the "5-in-1", "4-in-1", "9-in-1", "all in one", "highlights" tours. Here are links to just a few of them:
http://centralamerica.com/cr/tours/oneday.htm
http://www.viator.com/tours/Costa-Rica/Four-in-One-Best-of-Costa-Rica-from-San-Jose/d747-4100FIO
http://www.ecoscapetours.com/
They're all basically the same thing with the main difference being how or what they count as activities. Does the late afternoon/early evening drive back through Braulio Carillo really count as a visit to a cloud forest? I don't know what tour Orange was on but, unless you run into road or weather delays, these trips usually are "only" 11-12 hours long with a return closer to 6-7PM, though that is certainly still a very long day.
Yes, the butterfly garden on this tour is sometimes at the same place as the waterfalls (La Paz) as is a hummingbird garden. Does that count as 1 activity or 3? On some tours rather than do a real tour of La Paz, they just stop there briefly and have a longer stop at an eco-park (Selva Verde) on the Sarapiqui river that also has butterfly and hummingbird gardens.
All these stops really just scratch the surface. For example, the "coffee plantation" is often just a roadside stop near a patch of coffee plants where the guide gives a brief description of coffee growing, harvesting & processing, rather than the full tour of Britt or Doka where you actually walk through the processing plant. The various butterfly gardens are very pretty, but that is not quite the same thing as going to the Butterfly Farm where you really learn about the full life cycle of various species of butterfly. Of course, some or these all-in-1 tours spend more time at one or another place but that necessarily comes at the expense of time spent somewhere else.
Last comment, why aren't public bus trips on my list? Actually, personally I'd normally put these very high. In fact, I just spent the last MONTH travelling all over Central America by local chicken buses. In comparison to some of those, the buses in CR are downright civilized. The problem is that getting around by bus, while incredibly cheap, can be incredibly time consuming. Most likely you won't be able to easily combine a variety of destinations into a one day trip as you can (albeit ay considerably greater cost) with an organized group tour (or private driver or rental car). If that is not a problem and you don't mind knocking off one site per day (especially if you just figure you'll have many future trips to see all the rest), then this would be an interesting wa for some guys to go. It is sort of the polar opposite of the much more expensive all-in-one tour.