Backup strategy

[camner]

This is not directly a SuperDuper! question (it is relevant to any backup software), but I thought that the folks here have a particular interest and expertise in backup solutions. If I'm out of line in posting a question such as this, please forgive me and feel free to delete the post.

I've been using tower-based machines for years, and I currently have 4 hard drives in my tower. The first drive is my "main drive" which is partitioned into a main drive and a safety clone. The second drive is a periodically made backup (clone) of the main drive. The third drive contains backups made with a different product, and the 4th drive contains a bunch of photos.

I'm moving to an iMac, an all in one machine, and it only has 1 internal drive, and, of course, no room for expansion!

So, the question is what to do. Do I get 3 external drive enclosures? It seems wasteful (of power, of noise, and of time as the often sleeping drives spin up) to keep the external drives turned on all the time. Is there a way to keep them off and only powered on a little bit before the scheduled backup occurs?

Are there better solutions for backing up than just an external enclosure?

I'm looking for good ideas anywhere!