Thanks for the very helpful responses so far. There are some consistent choices there that are giving me a good idea where to start:
Secret of the Old Clock
Ghost Dogs of Moon Lake (like the idea of secret passages)
Blackmoor Manor (heard good things about it elsewhere also)
Last Train to Blue Mountain Canyon (looks good from the one comment above)
Anybody think I'm missing something? I'm a little wary of The Final Scene because of an apparent time limit- is that of concern? And, could some of you possibly grade the above in difficulty on a scale of 1 to 5- 5 being most difficult?
So many questions, but you guys are the experts!