As a "relapsed" maintainer, I'll second everything you've mentioned. My two big things are
Do: Plan Everything: food, exercise, rest
Don't: Live in Denial When you see that scale moving in the wrong direction - take action!
I realize now that I had never planned for maintenance. I just got to a decent weight/size, and ate and exercised the same as I had been while losing. This worked fine for about 18 months when 3 things happened:
(1) I lost my "controlled" environment. In 2000 when I was finishing my journey downward I was living in Seattle while my DH was in a cancer treatment program. We lived there for 8 months (Jan-Aug) virtually isolated from family, friends, and social events. We seldom went anywhere and so as long as I shopped well, I could eat right. Plus, I wasn't working. Most weeks I had plenty of time to exercise. There was a small gym in our apt building, a running track in a park a few blocks away, and given the traffic/parking situation I walked a lot of places. After awhile I got the opportunity to do temporary work which as a benefit let me join a really nice big gym in the same building for reduced rates. I ran a lot in the 8 months we were there, including several 5K races.
(2) In the late summer of 2001 I developed PF in my left foot. I had continued running and taking aerobic classes when we moved back home the year before and maintained my weight loss. Once I had the PF, I was unable to run, and basically stopped exercising, though I continued - mostly - to eat right.
(3) In the fall of 2001, I changed jobs. The job I'd had before I went to Seattle and when we came back was very active. I was an IT Tech in a building that was a converted old school. It's 3 stories, with only one - very slow - elevator in the center of the building. I was all over the building fixing people's computer problems, and unless I had to move a PC I used the stairs. I was up and down them all day long, and lifting lots of computer equipment. In October 2001 I changed to my current job - which I love much more - as a library director (which is what my degree is in - but life, as we all know, takes some interesting turns along the way. It's a whole nother story!). But this job requires a lot of sitting at a computer, sitting in meetings, etc. I walk around and stand a fair amount, but nothing like my old job.
Add to the above that we were now back home, living among our friends, going to social events again. After a year or so DH was able to go out again. I got less diligent about eating (never having actually been told much about maintenance). Slowly but steadily the weight came back. And I didn't weigh daily. It took a couple years before I went back to exercising regularly, and even longer before I "woke up" and realized that I had regained much of what I'd fought so hard to lose. Denial is a powerful tool. And even then it's taken me much much longer to get the fat moving than it did 6-7 years ago. Sigh. You'd think at my age I'd be smarter.
Now however, I've realized that no matter what I cannot just throw in the towel and let the pounds come back again. I have to do this the rest of my life if I want to enjoy the rest of my life. I see people my age (61) who are in much worse shape than I and I don't want to be there. To be fair, I was just on a vacation with Elderhostel in April and most of those folks - all 55 or over - were in great shape, able to hike several miles at 5K-6K feet. And so was I - made me feel great!

I want to keep feeling this way. My new hero is the geologist on the Elderhostel trip - he's 78 and still hiking most days!
