if we do "sky trek" or "sky walk" in monteverde, should we also do "hanging bridges" in arenal, or, are they very similar?

The hanging bridge canopy tours are pretty similar. The big difference is the view. From the Arenal hanging bridges you will see amazing views of arenal. From Sky Walk you will see lots of cloud forest. The actual vegetation is very similar. If you are just planning on doing the zip in the Santa Elena reserve (sky trek)you might want to do the walk in Arenal. Your chances of seeing wildlife and birds are much greater walking. Other options would be zip in Santa Elena, walking cloud forest tour in Monteverde, or visit Selvatura-they have both types of canopy tours also.
They are all good so you won't be disappointed.

Suzie2,
Do you know what can be seen from the Rainmaker Canopy walk in Quepos/Manuel Antonio area ? Would it be similar to any of the ones you mentioned ? Thanks.

Haven't done that one. It will be somewhat different because the others are cloud forest and Rainmaker is more in the rainforest. There are some differences in the types of things you see. Some different trees, etc. More monkeys I would think at Rainmaker. Most likely more iggies.

Thanks.