Someone mentioned the Hardy Boys books. They tried a retread a while back, but they sank without a trace as far as I know. Other series I enjoyed reading as a kid and did my best to find each and every book in the series:
Tom Corbett, Space Cadet. Actually a bit before my time, but copies could be found in the library and in used book stores. I think I found about 3 episodes on VHS tape, but as far as I know never made it to DVD. Not yet, anyway.
The Bobbsey Twins. OK = grade school reading, but...were fun. I don't think they ever tried to update / retread this one, though.
Nancy Drew - again, this one was re-released / retreaded / updated a while back, but sank like a stone because the new stories were pretty darn - umm... unreadable. Try to find the originals, and they do show up in used book stores now and then. Unfortunately the originals show their age really badly, worse than the Hardy Boys.
Tom Swift = again, they tried to retread this one, too, and it didn't get far. Of course, it also suffered from a type of 'power creep' in the series - the authors had to try and outdo each earlier book in inventions. Actually, I think the ones I remember reading were retreads of an earlier version, but done decently; the third iteration just wasn't up to the earlier standards.
Yeah, some of these are in hindsight pretty - juvenile, and not up to the standards of the stuff I'm reading now. But they were decent for what they were, and heck - I enjoyed them when I was in my early teens! I look at what kids have today, and - Twilight? Really? Give me Nancy Drew anyday over Twilight. Gah. Team Jacob? Team Edward? GIve me Team Thomas Raith, Team Angel, or best yet, Team Spike!!!' I'd love to see what any of those three would do to the 'sparkly vampires!"