First off, my trusty Mark II is my main body. I will be using my Fuji more (I talk more about that here!) My Canon has been with me for 3 years, and I love it. I send it in once a year for a checkup, it and just keeps shooting. While there are a few things I would change about it, it continues to be a trusty way to get my shots. A few close friends jokingly ask when I'm going to upgrade, or get out of Canon completely and embrace that cool new Sony A7- I do plan on upgrading to the Mark III here very soon, but as far as leaving Canon completely- I honestly don't see that happening anytime soon, if ever. I'm actually wondering when they'll stop fooling around and just come out with a mirrorless already.
As far as lenses, I love using my 50 1.2 for pretty much everything. It's my favorite focal length for weddings, engagements, small groups, fashion- almost anything I can think of, I always use my 50 as a starting point, and change focal lengths from there. My 100 2.8 is a great lens for portraits and details. It is completely versatile. I don't have to worry about camera to subject distance, because it will focus either way. I can shoot from a distance, get some great compression, OR shoot a little closer to the subject, crop in-camera and get a great tight headshot. For engagement sessions, I love getting ring shots- the beautiful bride-to-be looking up at her fiancé smiling, her hand showing off that gorgeous ring.... as with any prime, all I have to do is move my feet. For real versatility I love what my 24-70 does for me. If I'm in a tight spot, and I know there will be some issues with space, or if I know we'll be outside and my clients will want wide as well as tighter shots, I trust that the 24-70 can handle it. This was the first piece of L glass I bought, and while it's not 'version 2' it is still a really wonderful sharp piece of glass. I love prime glass though; I love using my feet to move in and out of a space. Zooms are great, but primes are greater. Give me a 50 and an 85- and I'll be shooting all day. I only use zooms out of convenience.
I don't upgrade at the drop of a hat either. I know there are several lenses that have had the second version come out- but my lenses work great for what I am capturing. They are all very sharp, and they just work. I'm sure someday if I try the 24-70 II, I'll think myself a fool for not upgrading sooner. I'm not always on the lookout for the next lens, the next body. If something works, I stick with it.
I have my trusty 580EXII, (we have 2 of them), and love them. We use them off camera, on camera, with a diffuser, without, they've survived falls, drops, mine even came crashing down onto our tile floor from 8 feet up. I sent it in to CPS and they repaired it- but it came back good as new, and is still firing. I don't see the need to go to the newer flash- yes I know the 600's do more- but these work just as well for what we use them for.