RE: When to move up?
Go to ailerons.
If you have experience building and enjoy the process, look at Mountain Models. The Smooth-E is a balsa fuselage and foam wing airplane that is getting rave reviews. If you prefer a built-up balsa wing try the Dandy Sport.
I don't know what plans they have for the Smooth-E, currently it's offered with a slow flying wing that will be sporting ailerons for those who want them, and a sport wing.
The Dandy has four wing options, three built-up and one foam: a polyhedral slow flyer wing, no ailerons; a sport wing; a GT wing which is a symmetrical airfoil and goes the next level in speed and maneuverability, and a new foam sport wing.
I have no experience with other step-up planes. I'm sure you'll have others contributing suggestions from the wide range of choices on the market.
If you want to explore a completely different kind of flying that's a blast, look at the SuperFly RC delta wings. I have both the SuperFly and the SuperFlea and they're very fun to fly once you get the hang of them. You can keep them close in and maneuvering the whole time.
Good luck! There's so much out there that the process of chossing is fun in itself.
Cheers!!!
BobbyG