I'm going to throw a thought out and let you all play around with it.
If you want to build an electric airplane, I'd go with the Kadet MKII or the Seniorita, and here's why:
1) They are both trainers, therefore they would be fairly easy to learn to fly with
2) If you decide to go with the foam power-glider first, everything you learn will easily cross over the the Kadets
3) They are fairly easy to build, the MKII being slab sided while the Seniorita is more of a stick build and slightly larger
4) Both are large enough to use full sized radio gear and larger battery packs so you won't have to worry about looking for micro this and micro that
5) Both would be easy to see due to their size and are known to perform well
6) Both are easily adaptable to be used in other ways than just a pure trainer, such as on floats, multi-engine, candy bomber, etc

Okay guys, you can shoot me down now