I recently saw an ad for a massage provider located in a building that contains a family member's office. Everyone in that office knows me, well. It's on a different floor from the spa, and I can get in the back door/fire exit so I'm not seen there. How bad of an idea is this? lol

Because you can't control the comings and goings of all the people in that office.  What if one of them is on a coffee break outside the building and sees you going in the back door?  Just one of several scenarios that results in you getting busted.

A man who doesn't spend time with his family can never be a real man.

Really, you've gotta ask. Ok, I'll tell you,  REALLY FUCKIN' BAD.

Be sure to stop in and say hi as well.

When they ask you what you're doing in the building, just tell them that you're banging some broad in the spa.

They'll howl with laughter.

could be going into a building 100 s of people live in . You could be visiting a friend. Which essentially is what goin to see a good provider should feel like. Anyways. I can see you feeling like nervous first time, Realistically. you think the odds are against you there d be a chance you may actually meet an old buddy whom truly lives there, seeing you may be by there on occasion anyhow with fam workin near by. In grand scheme of things you could alos be poppin in to have a look at an old treadmill you scoped out on craigs in for sale section. I myself have legitimately driven to places in my searches for maybe used fitness equipment or furniture, once i paid a friend 50 bux for a ride to this weird far away town, I forget name, i wanted to grab this bed fram i seen . advertised. i got thier, town was all huge huge mansions, bed was in front driveway, And dam it turned out to be a childrens bed! i was so bummed. i also couldnt even think of any one whom needed a brand new un used high end bed frame that was bein given away at time either, I ended up getn a super nice bed frame few months later any howbut any ways, point is, theres an awful lotta reasons why youd be goin into a apt building , who s to judge or even have time or energy to care why u r goin in. If your really concerned bring a big bag of take out say you are stoppin in to visit some guys from college to watch the dvd genie recording of the latest mma fights . or sumthin,
or you could get a pea pod delivery suit some how, and a box and dress up in the suit and pretend you are now workin partime for pea pod and this is one the people whom you have on delivery list.  
that may be like way too obvious, ,,,,,,also if you just like the adrenal rush, which it sounds like u do youl probly go to this locale over all others simply because your tapped and wanna play double 07.

ou are asking others what you should do as if you do not know what is good for you. Realistically, you are the only one who know your risks