Mention Spa Week and the treatment offered
To avoid any confusion, mention Spa Week and the treatment you'd like while booking your appointment. Spas only offer two or three treatments at a Spa Week discount but they offer dozens of others at full price so be specific and request an appointment for the treatment as it's listed on spaweek.org.
I went to Sothy's during fall spa week for a $50 facial. The facial was an abreviated version of what they usually give. I could pay extra for additional services, eg, clearing my pores, etc. They did try to get me to buy their products, but I said I'd think about it. In my experience, most spas will try to get you to buy their products regardless of if you're getting a deal or not. This year I've scheduled a facial at Fresh. The $50 I pay can be used to purchase one of their products, which I use anyway.
i've been doing spa week for years. it's twice a year, usually during mid-april (it's consistently during my birthday week) and mid-october. you check the spaweek page for your city, and go through the list of participating spas that are offering $50 treatments. really great way to test run a spa before you pay full price for services.
some spas will definitely try to pressure you to buy products; it's hard to tell which will and won't. a trick i use is that i go down that list of spas, find 3-5 that look good (always check that spa's website and look at the photos), and then look them up on citysearch.com. there's reviews from customers.
when you find the spa you want to try, call them and tell them when you want to go, and say you want the blah blah blah spa week treatment. you HAVE to call soon because those spots will fill up super quickly.
most of the treatments say 50 minutes or 45 minutes... they're really more than 35-45 minute treatments. they're abbreviated so don't expect anything thorough, especially with facials.
i've tried these spas during spa week:
dorit baxter -- pressured to buy products, rude receptionist/manager, but amazing body scrub every time.
nina's european spa -- horrible. INTENSE pressure to buy products, bad facial, loud reception, bad decor: part of the reception area is also a jewelry shop! BAD jewelry!
finesse day spa -- great facial last fall, no pressure to buy, very quiet.
shikuza (or shizuka new york.. i always forget which way it's spelled) -- it's not participating this spa week but amazing service and massage
hope this helps! i've already booked my appointments as a bday present to myself!