None of those mentioned are tours: you just call SkyTrek and make the reservation yourself, then show up. Same for Hanging Bridges (or just show up and buy the ticket, it's not that crowded). The waterfall is just a park and walk down, and back up thing, unless you want something like a horseback ride excursion to the falls.
Of course, if you have to add transportation, that would be an additional cost. But you can easily take a taxi to the waterfall and the Hanging Bridges (whether you choose the one near the dam or the one at SkyTrek). You can also get picked up by SkyTrek from your hotel: http://www.skyadventures.travel/Arenal_En/Sky_Trek.html

http://www.hangingbridges.com/rates/

Thanks! What about the Cano Negro reserve?

You could drive to Los Chiles and hire a boat for a private tour, but you'd probably be better off just getting a tour from town; there are lots of companies. http://www.arenal.net/tour/Cano-Negro-wildlife-refuge.htm
If Volcanogirl is lurking, I think that's an experienced voice for Cano Negro.

Yep, we've done Cano Negro several times. I'd recommend going with Sunset Tours; they do a great job. We've seen several varieties of monkeys there, as well as sloths, water birds, and caimans. I'd recommend bringing your own binoculars. For Sky Trek, we just booked our tour online for a specific time, and they came and picked us up at our hotel and dropped us back off. We did the Hanging Bridges on our own, but if you want to up your chances of seeing wildlife, I'd recommend hiring a guide; we didn't see anything there but ants, although it was a pretty hike. We did the waterfall on our own - took a taxi there, got the driver's phone number, and called him when we were ready to be picked up. If you want to look at organized tours, both Sunset Tours and Desafio have good websites. We've used both, and they're both great. The Penas Blancas river float is nice too, as is the Proyecto Asis animal rescue center, and rafting with Rios Tropicales. Lots of great activities in this area.

Nowadays, the mighty Arenal Volcano is still active, but its eruptions are now much less severe and occur in an almost daily basis. Surrounding lands are rich in hot spring waters warmed by the volcano’s volcanic veins.Some tour operator in Arenal are really good, I think is bored make plans by yourself , you are in vacation´s time , do not complicated .
check more info about tours : http://www.valledoradotours.cr/en/where-to-go/arenal-volcano.html
hope this helps!

"occur in an almost daily basis. "

This is not true.

Hands down the best tours IMO are run with Desafio - http://www.desafiocostarica.com/ they run many of their own tours so contacting them you are going direct in most cases.

Volcano has been quiet with no lava flow now for going on almost 2 years. Still vents gasses from the crater, and still IMO worth seeing, the whole area is nice.
Cheers

James, that's not really accurate information.

Yup, volcanogirl, he's been trolling on several CR threads; just a booster!

Thanks for the information, everyone!