I don't work with kids - but - I am a baby name geek.
Christopher/Kit - is a fairly timeless option. Although the Kit nickname is very now.
Isaac is quite current. May possibly date.
Toby is usually considered a slightly, um, wet name.
William. Lovely, classic, etc. Classmates are bound to catch onto 'Willy' at some point so as long as he can ride that out with aplomb, he's fine.
I would say though - that William is this generation's regal, timeless, classic name... What I mean is ... it's an old name, a very well-known name, a King's name, a classic. But even these names go in and out of fashion...
Richard is another regal, 'timeless', 'classic' but not many people are naming their boys it right now.
I don't think any of these names have 'naughty boy' associations, but am happy to be corrected. :)