I run something similar with 4 workspaces. I solved the "browser crashes taking down everything" problem by setting up 4 different profiles in firefox. Create a batch script to fire up firefox in the right profile for the right workspace.
It's worked well for me, when flash inevitably crashes it doesn't take the other workspaces with it, but it's perhaps not the most elegant of solutions.
1. Support Ticket workspace -- one for RT, more tabs for related research
2. internal wiki workspace -- one for the wiki, another for the wiki's github repo, another for a local build of the wiki
3. email / meetings -- one window for calendar+tasks, one for email, with and 1-2 extra tabs for documents or links sent my way
4. Site Reliability -- one for nagios alerts, one for site testing, one for munin, and one for github PRs
5. management -- weekly management meeting agenda google doc, a key report or two, and maybe a slides for a presentation I've been asked to give or review
Edit: IMO, I'm perfectly happy to give up Memory if it means one tab crashing doesn't kill the entire process. Even at 100MB per tab, 5GB is like under 50 bucks.