How best to edit long sections of footage?

After a week flailing in the darkness, maybe someone can point me in the right direction. I have many VHS and 8mm tapes dating back to 1986, each with up to 2.5 hours of footage.

They are all now safely saved on an external hard drive but I am having trouble when trying to edit them down into manageable chunks (clips).

I have iMovie 10 and Final Cut Express 4. I would like to systematically play through each tape from the hard drive and save, name and tag various clips for use in movies on different subjects e.g. holidays, individual family members, houses, friends etc.

I feel there must be a better, or quicker, method than repeatedly trawling through all the tapes and moving suitable clips to the timeline every time I want to make a movie on a different subject.

The hardware is an iMac from 2008 with 1TB storage.

Any suggestions eagerly anticipated.