I went through a similar period in my career. I spent the first 6 years of my career working on heavy industrial projects. Power plants, refineries, etc. Zero architectural consideration. Very low occupancy. My thoughts:
1) AISC has a good Design Guide on facade attachments to steel framed buildings. This is my personal area of weakness as early in my career I worked on a lot of "building like" non-building structures. But, they had no cladding.
2) Open web steel joists. This is used a lot for roofs and such for low rise commercial buildings whereas I never saw them in the heavy industrial projects. The best place to start with this stuff is the the following:
a) The Steel Joist Institute has a ton of resources available.
b) Vulcraft has their SJI spec and tables and such (free download?).
c) There is a short book / guide called "designing with Steel Joists, Joist Girders and Steel Deck". Jim Fisher is one of the authors. I can look it up for more details if you like.
d) There are some good Steel Tips and articles and such on camber which (in my experience) is more important for composite beam design than other things.
3) Composite Beam Design: These aren't as difficult as you might think. I'd start with the code itself. Then look at a bunch of details from a friend's drawings. And, play with a program that does composite beams (RAM, ETABS, RISAFloor or such)
4) Cold formed steel: Used a ton for partition walls and drop ceilings and such. I don't have a whole lot of suggestions on this. Hopefully someone else can pipe in.
5) Floor vibration. AISC design guide 11 is the main reference. But, other people will have "rules of thumb" and such that they use to try and avoid vibration issues.
I've focused mostly on commercial low rise buildings in my response. Mostly because you have to know a lot about those before you can extend your knowledge into mid rise which is more of the same, but probably with some additional considerations.