An idiot client
When you see a great campaign and are jealous that you didn't come up with the idea first, don't be amazed by it -- be amazed that some client approved it. There is a substantial knowledge gap on the client end in terms of what constitutes innovative marketing. It is an offshoot of the first-mover disadvantage. A client, due to its lack of knowledge regarding available technologies, might be amazed and approve something. Or, more likely, the client will force you to jump through so many hoops that the proposed program is no longer cost effective. Immediacy is the problem -- the need to have results now! But in many cases, corporate structures have grown into massively risk-averse entities. The client does not get a raise or promotion for doing something great -- rewards are only doled out for not doing anything bad.
This has resulted in a cult of client-side mediocrity.
The solution
Once again, stop going after the big idea. Educate the client on what's possible. Make your client a subject matter expert. Your client contacts know their business way better than any agency ever will -- they just don't know what media will most effectively reach their consumers. Set up education seminars at your agency on at least a monthly basis. Bring in vendors, technologists, and visionaries, and share information with the client. If you create an internal advocate, it's much more likely that your riskier ideas will get approved as they move up the food chain.
Start small. Build on small successes, and you will create a relationship where innovation is possible.
Also, request that your client create the same type of opportunities for you to learn its business. Trust me, the scope of what you do not know about your client's business and how it operates would stun a herd of buffalo.