Do you only have one computer? Is it a notebook or desktop? It's hard for me to relate to these kind of use cases, because I use many computers, several of which are notebooks. I could never use a workflow like you because I'd always be losing all that state.
Right now I use a 27" iMac at home almost exclusively, but there's a handful of other computers that I use in various locations, and several have persistent sessions (which makes gchat think I am available almost 24/7). It was more of a problem when I commuted every day, but I mostly just had different sets of things that I was looking at on each compy.
The Google Bookmark sync actually works pretty well between all of them for things that aren't transient. I just realized that there's probably a decent 'bookmarks sidebar' extension out there, and combined with "Open All Bookmarks in New Window" that could alleviate a lot of my project-related tabcruft.
I have indeed "lost all that state" many times over the years, but it hasn't happened since I switched to Chrome (It did corrupt its session once, but it keeps a backup). It happened every couple months with Firefox on Linux, though I couldn't dig as big of a hole since it crashed more than once per day on average.
Years ago when I used Safari as my main browser it didn't have session saving yet, I used a SIMBL extension that continuously saved all state (including the full DOM with no redownloading), but ironically caused it to crash much more frequently. In those days I would rotate between Safari, Camino, and Shiira using two at a time, so that when the primary started to fall over I could start a fresh session and let the tabs dwindle in the old ones until they could be quit.
Re: my usecase, I have a 26" 1920x1200 monitor on my workstatop, with a 15" Powerbook (running Debian, 1ghz G4) next to it that is basically dedicated to "always online" stuff like IRC, IM, and Identica, but never runs anything else and never moves.
Firefox 3.5.x is slower than hell on it, and I last time I tried, Chromium wouldn't build on PowerPC.
Having two heads on seperate machines comes in rather handy for managing workflow of concurrent complex tasks; as in, I can yell at someone on one while doing work on the other.
