The magic words are "I don't like strangers touching me." You're in the minority but it's not that uncommon. If spa isn't for you, don't go -- there's nothing wrong with that. Don't let anyone tell you otherwise.
As a full time stock trader, I have three monitors. Only one is for charts, a second is for a trading room {think chat room but people pay $200 a month so we don't have trolls} and a third for general browsing or reading stock related documents. At 4:15 when my trading is over, the two side monitors are shut off and the middle monitor is devoted to catching up on all the porn I missed during the day.
I've been on both ends of those at the spa, both as the receiver and as the attendant/massage therapist/clearner upper guy. I found the experience overrated.
A problem with too many massage therapists is that they have their own agenda; their own idea of what a good massage should be. They give you THEIR massage rather than your massage. What you want is someone who will ask you questions about what you need and what you like and do their best to give it to you. Keep in mind also, massage therapists aren't mind readers. If what they're doing isn't working for you it's OK to let them know.
Disclosure: guess what I did for a living for 20 years?
Got my AOL account in 1993, was laughed at continuously by friends until 1996. Today those same friends want to know why I have three monitors, how I set them up and why I spend so little time on Facebook.
Every single picture of my 13 year old self is embarrassing and there is no bribe or reward you can offer to get those pictures posted. Not even chocolate.