With BLT, hopefully they took care of most of the internal stuff like any new conduit and whatnot during the refurb, and now it's just a matter of survey and install new access points which should be pretty easy. You don't necessarily want to survey/plan before things are finished, as you just can't assume what things are going to be like, even if the floors all appear identical (back when my company did WiFi for some major hotels, we'd see install teams cut and paste floor surveys because they were "identical," we'd reject those and tell them to do a real survey).
Also, when I was last there I had to switch my laptop to 2.4 only, the 5 band was weak to nonexistent. That's the opposite of the advice I'd typically give for WiFi, possible some of the really horrible results/experiences might be because devices are latching onto a distant 5 band signal. Of course, this makes it even less attractive as a choice for work stuff, as permissions to change device settings are often locked down by company IT.