...and I "dont like" the idea of paying for hotel laundry (and I am travelling on my own dime)... any recommendations for a reliable laundry where one can drop the stuff and fetch them, all neatly ironed and clean...
Not sure which Plaza (hotel) in Kowloon are you staying at? Perhaps one of these:
1. Royal Plaza Hotel at 193 Prince Edward Road West, Kowloon
2. Harbour Plaza Hotel at 20 Tak Fung Street, Hung Hom, Kowloon
Neither of them are located in prime tourist areas, but as you mentioned that you will be out and wandering around, with the good public transit system in HK, the location should not be too much of an issue. Somone might have mentioned to me previously that the Royal Plaza hotel is frequented by mainland Chinese tourists.
Previous FlyerTalker has recommended a laundry at the Chungking Mansion on Nathan road, located a copuple blocks from the Peninsula hotel. The laundry is on the ground floor of the ChungKing Mansion, to the right at the end of the central corridor. Chungking Mansion houses many lower class hotels, and you will find plenty of information on Google. I took my family there to experience the atmosphere, and felt reasonably safe doing so.
I have used the laundry several times here, and they even delivered to the Hong Kong Intercontinental hotel a couple times with a small tip. The prices are (as I recall) shirt-HK$15, pants-HK$20, ready in about 2-3 days, add HK$5 per piece for next day. They can also do laundry by the pound, perhaps with a 5 pound minimum?, for a few HK$ per pound.
You probably will not want to go this far from your hotel for laundry, but I have noticed a few drycleaner/laundry in the general area near Nathan road, and I imagine the prices are probably similar for the drycleaners closer to your hotel.