It's like useful meditation...
I'll confess that I like cleaning my bike. I have a brush which is designed for cleaning alloy wheels on cars and it's great for getting into even the narrow gaps between frame and chain-guide. I only ever use warm water; no detergents as they usually contain salts in one form or another and, though they're no real risk on an alloy frame, if you have any rubber bushes or bearings (and you will) the salt will eventually cause the rubber to crack. Also, you'll have plenty of steel nuts, bolts and, of course, your chain. That said, although I have a Shimano chain I use a SRAM powerlink which means I can whip the chain off before dowsing the bike in water, and then clean it seperately. Only the main frame area gets water, though, and then only if it's heavy and slightly dried on. Stays get a wet cloth over them and the same goes for fork bottoms. If I can avoid getting running water near the headset or hub bearings then I do.
I agree with Fred on the WD40. I have good quality grease, carefully put in, on or around all the right places and there's no way I'm going to start washing it out with WD. Saying that, if I get in real late after a wet ride I'll take my chain of, drop it on a plastic tray and give it a quick spray to disperse the water from the bearings. It'll get a proper clean and lube the next day. The rear mech gets the same treatment. WD40 should have a warning to cyclists, I'm sure it does way, way more harm than good on bikes.
One last thing, I usually do a big strip down towards the end of Autumn. It can get very wet in the UK that time of year and I learned early on in my cycling life that taking taking some good, thick grease to every bolt and thread on my bike before the wet months will save me, and my bike, a whole lot of trouble and wear.
Close attention to keeping a bike clean also means close attention to all its components, so you get to keep an eye on wear and tear. You also learn how to take things apart, how they work and how to put 'em back together.
Peace,
Steve.