Hmmm...

Tiger (40 or 60) (Phoenix or CG). CG Tiger ARFs are not avail from Tower, you will find them elsewhere
Phoenix Dolphin- Its ideal second plane. 61" wing span and relatively sturdily built for "cheap chinese" models. Its well suited for grass fields, just put a bigger tailwheel and reinforce all the joints you can reach with CA and add stiffners to the sides of the fuse hatch
WM Super Sporster: Also very good but 59" span
GP Easysport- its a great plane to fly
GP /H9 Stik / Bigstik: These are good airplanes and are sturdy because they have a simple box type construction

Or you can go all out and get a UCD 40 or 60. Though they are 3D in intent, you can fly them like sports airplanes with the low throws. They are fun because they are practically unstallable. And they (need to) fly very slow so you have more time to react if you make a mistake

Ameyam