Try www.dynamictravel.com.
We just booked a 31 night cruise on the Orient line with them, and was pleased with the service. (Julie was the one that helped us). They do not charge a service fee like a lot of the interline agencies do. I haven't found one that has better prices nor better service to warrant paying even a $20-$50 fee. None I have used in 12 years will dazzle you with their service.

You can sign up at Dynamic's web site to receive their email each week listing hot specials. Most of the agencies have the exact same deals, and prices are almost always the same.

I wouldn't hesitate suggesting Dynamic. Let me know if you want other specific ones or if you have other questions.

Good luck.