I wouldn't do nitro for a first flyer. Honestly, in anything under a 60 size I still think electric is the way to go. I had two nitro planes that I converted to electric and don't regret the switch - I hated the smell, cost of fuel, etc, etc. I can get to a flying field and be in the air in under 5 minutes...that's something very few nitros can claim (at least on a regular basis). Run times can be solved by more batteries (if the plane is big enough to hold them). My Kadet Sr flew with a 4s 10000mah battery. Full power flight times were in excess of 45 minutes, and when flying slower and catching thermals at least one flight exceeded 2 hours.
For trainers, typically any "high wing" design with a brushless motor will be acceptable. Foamy traines are easier to repair that stick builds; but they are usually pretty light so they "dance" a little in the air and can't fly in as high of winds.
Always keep the airplane upwind of you, that way if you lose power or the wind becomes too strong you can still get it back to you.
If you're interested in assembling the plane, I'd look at one of the Sig Kadet variants. You can get them in ARF form...but there will still be some assembly and electronics required to get them flying. If you want RTF or PNP then airplanes like the Cub already suggested will be good (I prefer the HobbyZone/ParkZone). Warbird type airplanes, while great looking are not good trainers.