The Apogee aspire, inexpensive kit(little over $15), flys on anything from a C11 to a G80, flights of over 1 mile high(literally!) on an F10, has a 29mm motor mount for E-G motors, but comes with a 24mm adaptor for C-E motors, you can use standard Estes/Quest launch equipment for C and D flights, but for E to G flights you'll want a sturdier launchpad and a little more cable on your launch controller to put you a safe distance away, this is most likely the highest flying hobby class rocket kit period, I have no actual experience with this kit, but if the specs are correct and it really does only weigh 1.85oz then I can see why!
Go to
https://www.apogeerockets.com/aspire_rocket.asp
to see it... and buy it if it's what you're lookin' for.
As to your question about whats after hobby class(low power rockets) well, that's simple.... mid power rockets! These fly on E through G motors, and as you can see by the rocket kit description above they're 'not always' bigger/heavier/more expensive than low power kits(but usually they are), they're no harder to build than your garden variety Estes/Quest kits... and sometimes even EASIER to build because the quality in the fit and finish of the parts is usually MUCH better than Estes or Quest.
After you get bored with Mid power rocketry then you step into High power rocketry, and this my friend is a whole new ballgame, HPR is where things can start to get conusing to a newcomer, HPR is divided into three power classes(Level 1, Level 2, and Level 3), and ALL require thier own certification in order to be allowed to purchase motors in the power range for a particular class, and to make it even tougher ALL HPR motors require a Low Explosives Users Permit(LEUP) from the Buearu of Alcohol Tobacco and Firearms(BATF) in order to legally own, use, transport, and store. Level-1 HPR motors consist of anything from H to I, Level-2 is J through L, and Level-3 is M through O. As to the rocket kits themselves, they're fully legal for anyone to own and build, and applying the same rule in the above paragraph HPR kits are usually 'but NOT always' bigger/heavier/more expensive than mid-power kits, HPR kits usually use heavier and tougher materials to stand up to the higher stress placed on them by the more powerfull motors, but again, they're no harder to build than your standard Estes/Quest kit, you just have to make sure you build them STRONG, throw out the white glue and plastic cement cause it has no place in HPR, if you wanna build an HPR kit you need a good strong epoxy.
