Agency contract work, good or bad? You decide...
goldfingerknuckle.tumblr.com
goldfingerknuckle.tumblr.com
Yes, generally you can command a higher "agency" rate than with most other clients. They have deeper pockets generally, but raising your rates just because you can is a little unethical. The reality is that the agency is at the mercy of the client and both parties are fighting hundreds of constantly changing (usually unseen) variables, and so they are willing to pay a premium in the interest of getting things done on time and done well. So yes, you will have to unexpectedly work on weekends, or work on requirements that sound backwards or are overly complex, but you will be compensated for that extra effort.
Also, unlike some of your non-agency clients, you may often be exposed to projects that are "award-winning", or will have an enormous audience, or take advantage of some new, hot technology. If you have the luxury to pick and choose these projects, then absolutely work with agencies. Otherwise, be very cautious about getting your schedule overrun with bizarre requests and drawn-out initiatives, and not being able to focus on your consulting practice or product development.