I gotta say that I prefer aluminum rims (they stay in-true better, plus they're lighter, plus there's a reason why, for the past 30 yeas, only the most wretched bikes come with steel wheels.... the cheapest dept store bikes, and industrial bikes.... which makes sense b/c neither is expected to perform. I've never had a problem with tires blowing off aluminum rims, and I like the weight/strength of the aluminum rims I run. That being said, the moped-like steel rims that come stock on a Worksman are impressive to behold... and every bit as heavy as they look.
As for tires, I like volume and knobs for offroad, just like virtually everyone likes for their offroad bikes. While skinnier knobs are lightning fast on certain trails (ever try to keep up with a cyclocross guy on well-groomed singletrack? They're amazingly fast, on 700x32c knobby tires...amazing), having a little cushion for the pushin' is a big help on most trails. For clearance reasons, I tend to run between 2.1 and 2.35" knobbies... I'm a huge fan of Kenda Nevegals, but I like my Panaracer Fires and I had really nice results with the front/rear specific Kenda Kinetics. I'm working on a Schwinn Heavy Duti, which has clearance for days, and i'm thinking of trying some 2.5 or 2.7" Nevegals on that one.
Everyone has different preferences, and different trail conditions will inform those preferences. IF I only had one bike (scary though), I'd likely have half a dozen wheelsets, each shod with whatever tires I prefer for a given type of riding. (Hookworms for the street, Fat Nevegals for technical trails, smaller 1.95" Small Block 8s for fast/flowy trails, whatever.... probably have different size sprockets on each wheelset, too, for gearing options....
Luckily, I have a few bikes, so I can set them up for their intended purpose and leave'm that way....