I agree strongly with Hokie's assessment with one possible exception: the conclusion.
I'm actually in the reverse position. I'm considering migrating from general EOR work towards facade engineering because I feel that structural EOR work has become too much of a commodity in my area. Those of us selling EOR services in my neck of the woods basically have one lever to pull because our products are pretty much indistinguishable: relationship based selling. That's all fine and good but, as any MBA will tell you, RELATIONSHIPS + IN DEMAND PRODUCT is a much healthier position to be in. Much. I consider facade/envelope work to be such an in demand product.
While I empathize with your desire to be good at the things that structural engineers are typically versed in, I expect that you'll find the reality of the design work in those areas a bit disappointing. In a modern design office, steel and concrete design basically amounts to pounding out a RAM/ETABS model and slapping together a bunch of typical details. There just isn't time or fee available for much more. Like you, I'm very interested in understanding the art of excellent concrete and steel design and detailing. In fact, I'd say that I'm a good deal more interested in it than your average EOR. That said, virtually all of what I've accomplished in those arenas has come on my own time, not really "on the job". I will concede that schematic design of steel and concrete systems is pretty satisfying and demands of good deal of skill.
Having been in the game a while, these are a few engineering career development principles that I've come to accept as true:
1) If you want to make any real money, or exert any real control over your destiny, you need an ownership stake in your company. That pretty much means either starting your own gig with or without partners or becoming a principal in a firm where you are able to acquire equity shares in the firm in a meaningful sense (profit distribution and some measure of strategic input).
2) Unless you bring something very special to the table, you usually have to do three things to make principal at a good firm. The first is bring in work. The second is execute that work profitably. The third is to pay your dues by simply being a the company for a good long while so that they trust you with their big projects, big clients, and talented staff.
3) That something special that you might bring to the table at an EOR firm may very well be facade design experience. I know a number of folks who took that route and made it to principal at premier EOR firms way faster than they would have on the EOR path. In theory, these guys now have the option of doing whatever they like (facade, steel, concrete). In practice, not one of them does anything other than facade work and maybe a little forensics. I suspect that the reason for that is that doing principal level facade work beats the heck out of doing designer/PM level concrete and steel work any day of the week.
4) It's surprisingly hard to switch gears within structural engineering in my opinion. Whatever folks start off doing, they usually keep doing. The end. You quickly end up only being valuable at the things you already know how to do and with the clients that already trust you. It's a terrifying thing for new grads to hear but, truly, I cannot overestimate the importance of the first few work engagements that make up your career. They set the tone. Just ask the poor bastards who get started during massive recessions. They often end up a decade behind their peers permanent.y
Considering "truths" one through four together, I come to this recommendation for you:
Step 1) Do your darnedest to figure out what the heck you want to do.
Step 2) Do your darnedest to figure out who the heck you'd like to do this with (perhaps yourself).
Step 3) Start doing these things yesterday.
If it's the case that you need to dabble a bit in order to figure out what you want, then that's just what you'll have to do and there's not much getting around it. That said, being a diverse jack of all trades is usually a road to the middle. Kicking ass at a valuable specialization (facade or EOR) is a pretty reliable road to the top. Although, it's important to recognize that almost nobody gets to the top being a great EOR designer. Because of the commodity problem, EOR's have to climb the ladder by managing and developing good designers rather than actually being them.
I apppologize if I'm telegraphing a lot of industry pessimism here. I am nothing if not a product of my environment and experiences.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.