I have used both aluminum and stainless steel. I prefer the later which does have an aluminum disc at the base (tri-clad SS kettles). I prefer SS’s aesthetics and cooler handles (to the touch). Aluminum conducts heat so well, in fact, that I have stupidly burned my hands on the handles during my lapses in attention. I now have oven mitts and or leather gloves in my brew gear to prevent this—I use the leather gloves when working with the hot kettle and liquids as it also has saved me from burning my hands on hot wort chillers or spigots or splashes. It also gives me more confidence with my grip. I realize that it makes me look like a wide receiver, but I don’t care. I hate burns and my hands are important in my work.http://www.instawares.com/nsf-stainless-steel-stock.rii-royssrspt80.0.7.htm
Royal NSF SS stock pot with lid, 80 quarts (20 gallons) = $181.69 (ships free). http://www.amazon.com/Pro-Quality-Titanium-Step-Drill/dp/B000RP82F8/ref=sr_1_12?ie=UTF8&s=hi&qid=1275570805&sr=1-12
Pro Quality Titanium Step Drill Bit 7/16” – 1-1/8” by 1/16” increments = $6.25 + $4.75 S/H ($11 total)
[If you want to make a spigot for your SS Kettle, you’ll need a 7/8” hole in your SS kettle located about 1.5 inches up from the bottom (on center). You will need this extra room for the washer that goes on the inside of the kettle with the weldless SS valve. This drill bit and your 3V corded drill at home will do this perfectly—just wear safety glasses when you do it. I put the spigot directly below one of the handles on the SS kettle since I wanted to be able to carry the kettle w/o fear of knocking the spigot and to have the ability to lift the kettle with just the opposite handle (i.e., tilt the kettle) to encourage drainage]. To finish off the hole, I used the drill bit from both ends (i.e., outside the kettle and inside the kettle)—taking care to keep the bit perpendicular to the hole/kettle wall—in order to de-burr the edges of the hole. There was no need to use 3-in-1 machine oil (though some recommend it) or a metal file. My dremel was worthless for deburring—use the drill bit with light pressure from both sides of the kettle—it makes a perfect, symmetrical, and clean hole. Just take your sweet time and do it right. Periodically test the size of the bulkhead fitting through the hole; you want it to be a snug fit. The hardest part for me was the overcoming the mental aspect of drilling a hole in such a beautiful kettle!http://cgi.ebay.com/Weldless-Stainless-Steel-Valve-and-Spigot-Free-Shipping-/380122770975?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item5881152e1f
Weldless SS valve and spigot = $47.50 (ships free)
Total cost: $240.19
I personally use the cheap metal or digital thermometers that run around $10 and don’t have much use for a sight glass since I boil at ground level and look into the top. I have my spouse or a brew buddy help me lift the kettle to a higher location (e.g., table top or tailgate) after chilling to facilitate gravity transfers.
If you want to have the beautiful Blichman Boilermaker 20 gallon brewpot (spigot, thermometer, sightglass), then it will cost you about $400. If you do it yourself, you save about $150.http://www.rebelbrewer.com/shoppingcart/products/Boilermaker-Brew-Pot-%252d-20-Gallon.htm
The big thing for you will be weight. Aluminum pots are lighter than SS (a 20 gallon Aluminum pot is 16.5 lbs, while a SS pot is 36 lbs). I like the 20 gallon kettles because it allows for easy brewing w/o boilovers of 10 gallons batches of any targeted SG you desire. You’ll only be limited by how much grain you can stuff in your 10 gallon Igloo/Gott cooler or the larger rectangular coolers.
One US gallon of water weighs 8.35 lbs. So lifting a 20 gallon SS kettle (36 lbs w lid) with 10 gallons of 1.050 SG wort (8.35 lbs x 10 gallons x 1.050 SG = 87.7 lbs) would mean lifting 123.7 lbs.
Lifting a 20 gallon kettle with 15 gallons of wort (e.g., at pre-boil) means lifting 167.5 lbs (36 + 131.5 = 167.5). Given the weight and bulk—any lifting or transfers should be a two person job (with the lid on). I’ve done it alone once, but it wasn’t pretty and I won’t do it again. There’s no way to lift it alone w/o having to prop the hot kettle against some part of your body during the lifting process.