I usually start with MPSIMS, then jump over to the Cafe.
After that it is a toss up between IMHO and the Pit.
If I have time, I then go over to General Questions, and finally Great Debates.
The other forums, I only go to every once in a great while.
I read pretty much MPSIMS exclusively any more. Once in awhile, I’ll hop over to the Pit or IMHO or Cafe. Only rarely will I hit GQ, GD, or anything else. I just don’t feel qualified for anything other than the mundane.
Start at ATMB, skip to GQ, skip to CS (usually; sometimes I’ll check out what is brewing in GD), then on through.
MPSIMS
Pit
Cafe
ATMB
IMHO
GQ
Only rarely do I venture into GD. It’s always the same ol’-same ol’ in there. “I’m right.” “No, I’m right.” “No, you’re wrong. I’m right.” Blah. Blah. Blah. 
Happy
IMHO is usually first. This is where I usually find the most interesting threads and the ones to which I feel I am qualified to respond.
MPSIMS comes next, pretty much for the same reasons as listed in IMHO.
The Pit comes after MPSIMS. I’m more selective about the threads I view and post to, especially if I am at work, given the nature of such threads.
General Questions comes fourth. I find a lot of interesting topics and responses, but I don’t usually know enough about the questions asked to offer a knowledgeable reply other than one that is anecdotal to the OP.
Cafe Society comes fifth (sometimes it precedes GQ). I don’t watch a lot of TV and I have only seen about half as many movies as most other people (but would like to see more if I had the time). I tend to watch for the music-related threads the most.
ATMB and Comments on Cecil’s Columns I only visit occasionally, if the other forums are tapped out for me.
Great Debates I never visit this forum. I’m just not the debating kind of person.
General Questions
Cafe
In my humble opinion
MPSIMS
Pit
Always. I am so boring, routine routine… I never dare go to GD!
I usually have two browser windows open when I look at the SDMB, so my order is:
MPSIMS and Pit
IMHO and GQ
MPSIMS and Pit again in case someone posted since I last checked
repeat
If I’m really bored, I’ll look at GD and Cafe Society, but I rarely find threads that interest me.
Historically, it’s been Great Debates, Cafe Society, In my Humble Opinion, MPSIMS. Lately, however, I’ve been going to Cafe Society first to read the latest posts in the “If LotR had been written by someone else” thread.
I start a the top and look at them all (but I generally only post in CS, IMHO and the PIT).
And here, jeez what the hell was I thinking?
unclviny
:o
Pit
MPSIMS
IMHO
Great Debates
General Questions, then I’ll poke 'round Staff Reports, Comments, Cafe, and ATMB now and again. Just to see if there’s anything new or interesting or both.
Some days I don’t manage to ever climb out of the Pit.
What d’ya expect, given my username?
Cafe Society (even without a TV, I find I can absorb most of the threads)
IMHO
Pit
GQ
MPSIMS
GD
ATMB
and oh yeah, the Cecil stuff
Pit
MPSIMS
IMHO
GQ
GD
A couple of times a week I’ll check ATMB after reading GQ and occasionally I’ll read CS.
I do it in order, from most favorite to least: General Questions, About This Message Board, Comments on Cecil’s Columns and Comments on Staff Reports (sometimes), Cafe Society, In My Humble Opinion, and at last, the lowly MPSIMS. Half the time, by the time I get to Cafe Society, I’m only reading threads that are grey (as in, ones I’ve read before). If I accidentally click on Great Debates, I’ll read a thread.
Cafe always first.
Then either IMHO-MPSIMS-BBQ-GQ or GQ-IMHO-MPSIMS-BBQ
Only drop in on GD every so often.
I start with GQ, then CS. For the rest, I click on View New Posts and see if any thread titles look interesting.
IMHO
MPSIMS
GD
GQ
BBQ
CS
I work my way up the order listed, starting at the Pit and moving steadily upward to ATMB.
Then, if I’m just passing the time at work, I go to ‘Show New Threads’ and just keep reading and refreshing.
For the most part I start with Cafe, head to the Pit,then just work my way to IMHO and MPSIMS. Rarely do I go into GQ or GD, almost never GD. The posts there are too involved for me to get into, I wouldn’t contribute anything. I don’t know anything so GQ is for my information only.
I usually start at the Pit and just work my way up the forums in order. Most of the time, however, I click on the “view new posts” thing and view the threads like that.
I’d say I post in MPSIMS the most, but I really don’t post that often.