Scubasteve,
Even with my set-up below, I find it easier to have 3 "stock pots" heating water on the stove for the sparge while I mash. Saves on trips to the propane dealer.
My real reason to post was because of your comment about wanting a "grown up" system. My advice is (1) know what you want (2) set aside some cash and (3) watch Craigslist relentlessly (check out list-alert.com for "help").
I knew I wanted to jump to triple batches (15+ gallons to fermenters). Which means larger than keggle systems. My system below showed up about 125 miles from my home but after a few emails and a call I knew it was exactly (almost) what I wanted.
21 gallon HLT, MT and BK. 1 March pump. Quick disconnects and cheap (subsequently replaced) silicon hoses. Brew station on wheels with three 155k propane burners. All for $500! I have probably spent another $3-400 getting the other stuff I needed (more fermenters, more bottles (I don't keg), a BIG immersion chiller at stainlessbrewing.com, good hoses, a 2nd propane tank etc). But I have 15 gallons of wort from a 10 hour (start to finish) brew day. I figure I can make a bottled bottle of beer in about 6 minutes @. (I know, odd stat but I used to invest 15 minutes@ with my 5 gallon system).
Anyhow, I have scored big twice on craigslist but you have to be ready.
BTW, at this point I do a 1 big fairly soupy mash that fills the MT with 40# of grain. Then fill it to the rim again for a batch sparge. Pump about 17.5 gallons total over to BK which yields 15 gallons to fermenters. (and sometimes a couple gallons extra wort which I freeze and make kitchen sink beer from when I've accumulated 7 or 8 gallons and need freezer space back.)
Good luck and I hope you find this a little inspirational!