Avoid the hotel laundry service
Hotel laundry services are obscenely overpriced
This is the biggest rip-off at the hotel. Oh, sure, the phone charges are the most insidious—because the phone is one of life's daily necessities, plus unlike with minibar or laundry, they don't warn you with a price list first—but in terms of outright overcharging, the hotel laundry service just might be the worst.
We're talking on the order of $3–$5 per item to have a t-shirt or pair of pants washed, or $6–$10 for a dress. Heck, they'll even charge $1–$3 for a single pair of socks or a single pair of underwear.
OK. Let's assume you followed my packing list, and that you are going to wear one set of clothes while washing the rest—and that you won't bother washing the sports coat or sweater you brought alone for warmth and style. That means, to wash a single load of travel laundry (pair of pants, pair of shorts you used to swim in, two T-shirts, a long-sleeved shirt, a skirt, and three pairs each of socks and undies) it would cost about $26. Heck, in a Queens laundromat it only costs me $1.25 for the washer and another $1 or so for the dryer for a load that small.
The solution? Two choices. One is to seek out a local laundromat, either coin-op, or a place that does it for you—though watch out for the latter, as they usually also charge by the piece (if not quite so much). You want to find one that charges by weight. Either way, expect to pay less than €15 to wash and dry your clothes. Bonus: many laundromats now double as cybercafes. (Actually, there are some hotels—guess which kind? Yep, the cheap mom-and-pop ones—which will do your laundry for a nominal fee about equal to what a local laundromat costs.).
The truly frugal option is to do your own laundry in the bathroom sink. Just put together a basic travel laundry kit: Get some cheap, biodegradable washing solution, such as Campsuds, and a braided clothesline (both available at camping/luggage stores and through travel catalogs), and be prepared to do a bit of washing up each night before hitting the sack.
Ninety seconds of scrubbing and wringing them out sure beats paying $3 just for some clean underwear.
Hang the wet clothes to dry overnight; on the balcony if you have one and it's warm, over the radiator in winter (I stuff socks and undies in the radiator cracks, then drape shirts and pants over the top).
I usually do this for about two weeks at a spell before taking the lot of it to a laundromat to get a more thorough washing.
The only problem is, lots of hotels don't like you doing this (uses up hot water, plus I'm sure the lint collects to clog the drains), and some even post nasty little signs in the bathroom scolding you against the practice.
To me, that just means I have to be sneakier about it and can't leave the stuff hanging in the room all day for the maids to find.