I'd say our boundaries have been pretty solidly laid down at this point, in the sense that we know what the relationship is and what it isn't. There may, at some point, be an extension of the boundaries past where they already are, but I don't foresee that happening in the immediate future.
That's a start, but boundaries are only part of what I mean. Boundaries mark off where you don't want to go, but taken alone they leave everything inside their limit still undefined. In other words defining what you don't want is crucial, but so is defining what you do want.
To extend the art analogy, if you asked me how to paint a picture I'd say first decide what you want to paint. That decision by itself will make many of the "how" choices clear.
I suppose I'm primarily looking for views on the comparative merits and demerits of a highly structured routine vs. a more freeform one(yeah, I know that's vague, sorry).
My answer assumes that by structure you mean rules and how strictly they're applied or interpreted. Generally speaking the advantage of a lot of structure is clarity. Both of you tend to understand better what's expected of you in any given situation. From the Top side this offers a strong feeling of, well, Toppiness for want of a better term. From the bottom side it offers a lot of security and a sense of being looked after, cared for. It feels like the Top's attention is present even when the Top is not.
The downsides to structure are less flexibility and more work. While a structured relationship gives more clarity in most situations, it's harder to adapt to situations that aren't covered in the rules. Likewise, the more control the Top takes, the more responsibility he or she assumes.
Lack of structure has the opposite pluses and minuses. It gives less of a sense of immediacy to the bottom, but more autonomy to serve both the Top's needs and the bottom's own needs. It's less hands-on control for the Top, but a lot more time to relax.
My advice would be to start not with "how much structure," but rather "where is structure important?" There will be certain times, or certain aspects of your relationship, where both of you want rules. And there will be other times where they just add more effort than either of you think is worthwhile.