On the Mac (of which I have two, so you could say I'm a regular and keen user), I don't bother with Safari but instead use OmniWeb, a non-free third party browser. It's packed with features to help juggle dozens of open pages at a time, and other things besides, so is a good power alternative to Safari.
OmniWeb is generally very stable (or at least has got a lot better in recent months), although painfully slow to start. That's its most brain-dead feature (a side effect of the workspaces feature). What I really do like is the easy management of popup and cookie preferences per page/window/site, and the tab thumbnails.
It looks like there may be a new contender for OmniWeb's title as the power browser for mac - Shiira. This is based on the Apple Web Kit so is basically like Safari 3 inside, but with added bells and whisles. This one's Free and free, and with the recent release of version 2, looks like something to keep an eye on. I'm submitting this post from Shiira.