For what it's worth, I also have been accumulating all kinds of equipment, and here's what gets the most use ...
I am always using my individual dumbbells up to 25 pounds; the 30-35 pounders not as much. That's about the time the adjustable dumbbells become useful. I bought the adjustables to save floor space, for 35+ situations. By the way, pace mates are great for tweaking metal dumbbells by 1-3 pounds; that plus weighted gloves will get you any increment you like. If I had it to do again, I'd buy only metal dumbbells.
The barbell plus squat rack comes out all the time since I bought it. I love it especially for Meso 3squat rack legs. Regardless of DVD, though, the bar is far more comfortable for me than heavy dumbbells when doing lunges and squats. My arms were getting overstressed from holding weights during squats; that's because I often need to do Legs/upper body back to back on the weekends to fit them in between travels. Also, when doing a full body workout that combines upper/lower, the bar gives my arms a bit of a break when working legs. The squat rack plus bar eliminated that problem. It is also fun to 'clean and press' with a barbell - more satisfying somehow than dumbbells! Before getting squat racks, I went with the barbell plus a heavy vest, which also worked well. Deadlifts go better for me with the bar than dumbbells, too, though partly that's because my adjustables are so wide. It isn't a bad idea to go back and forth between dumbbells and bars, to avoid having one arm take over for the other. I really noticed I'd been neglecting that advice when I started with kettlebells.
BTW, I absolutely love my Manta and Sting Ray for bar comfort in back squats and front squats. Much nicer even than a bar pad in my opinion, though far more expensive. The Lockjaw weight clip is wonderful for quick changes and fits nice and snug on the bar - another expensive but worth it purchase. VersaGripps are nice for deadlifts that get heavy.
I've actually got two bars now. My walmart bar was great for a year after I bought it: smaller, inexpensive, and vinyl so it could rest on my floor. It was four pounds plus a set of 100 pounds of weight. After the first year, it began to bend slightly. That's probalby because my deadlifts were getting towards the upper limit what the bar could handle (140 pounds is the rated max for that particular bar; it gave me trouble around 130 pounds). I shifted my original bar to upper body only, and bought a Cap, which is longer/heavier/more awkward to store, but is rated to 250 pounds. My back squats with using rack just hit 170 and my goal is to get to 200 pounds by the end of the year, so this should last me awhile. I have not regretted going with the universal rather than olympic size plates, at least not yet.
For wrist comfort on other upper body lifts, I prefer dumbbells, and I usually use them for bicep curls and the like. My wrists are happier when I vary the angle. The adjustables are a little large, but usable.
All of that equipment does take up a lot of storage space! It would also have been prohibatively expensive to acquire all at once - I bought it over course of several years, with an eye out for sales. You can do quite a bit with a weighted vest plus dumbbells up to 25-ish pounds, and a good set of adjustables. Also, if you get a barbell, you might also want the bar-style hand weight instead of adjustables. That would let you use the same plates on each. The bar-style hand weights seemed to rattle a bit when I tried them in the store, but it was probably because I didn't have the weight clamp on tight enough.
