There are numerous places to look.

Try http://www.modelaircraft.org/plans.aspx
That is the Academy of Model Aeronautics (AMA) plan service. Somewhat difficult to navigate but lots of stuff there.

http://www.easybuiltmodels.com/#top This is the Easy Built model line. Depending on what you have in mind, there are numerous model here that can be built into great RC models. BTDT. Glow or electric. Take the kit, especially the 50" wingspan ones, add some beefing up and you have a fine flying model, however you need to be a builder to do so.

[email protected] for precision-cut kits and also Palmer Plans and Don Smith plans. www.precisioncutkits.com Don't be in a hurry!

Lots of options out there. Good luck.