"Classic" has never existed on Intel Macs since it's a virtual machine that only works on PPC CPUs. I'm not a big fan of Classic mode as my experience with a lot of programs has been poor, but it's still fascinating to me that a G5 Quad built in 2006 could run a program written for the original Macintosh in 1984. In one fell swoop, that died, and even more backward compatibility went away in 2011 with Lion.
All of that aside, I agree that an old PowerBook or iBook is your best option. I like the Clamshells for old games due to their screen resolution, but that's a personal preference and have become enough of a collectors item that you may not want to spend the money.
Aside from that, there are a couple of emulators around that will let you run on an Intel Mac. Sheepsaver is one of the more popular ones.
Personally, I still have my Tandy 5 1/4" Carmen Sandiego disks...I bought a Tandy 1000 several months ago, but a friend a few states away still has it and hasn't had a chance to ship it yet. I'm looking forward to reliving some fun memories from my childhood, and that's one of the games on the list!