I've always found Seafoam to be good... I like the spray in stuff, warm up the engine, shut it down, soak the carbs/throttle bodies with it (like, soak them), start the engine, rev it up a bit (3-5k is fine) and watch the smoke pour out on a bike with any serious mileage. once it starts smoking less, then i'll leave it running and rev'd a bit, and spray more into each throttle body/carb. usually notice a decent difference.
The in the gas tank version seems to work alright, I use it but I don't notice as much difference. You can also induct it into the system by pulling a vacuum line at the right place and quickly dipping the line in and out of the can, which will suck some into the intake directly.
getting the injectors cleaned properly is well worth it though, that in combo with the spray out stuff should clean out any carbon anywhere important.