Keith...
One course I am really interested to play is Highlands Links in Canada. I haven't seen many pictures or heard too many people talk about it...but one aspects I've read about is its routing. I read that there are some long green to tee transitions, but they make the those walks like nature walks and they are actually a positive aspect of the course. Anyway, that is what I've read and I am interested to check it out.
And as for my 2 cents on what is acceptable on green to tee transitions, it centers on the flow of the course. If the course feels like it starts and stops, then I don't like it. If it flows...I'm okay with it. For example, I've played many courses (mainly courses designed for golf carts) where you play a hole (and the hole can be really good) but then you stop, get in a cart or walk across a neighborhood street, through someone's yard, to get to the next tee box. This kills the flow as mentally I shift out of playing golf for the time I make the transition and then have to get re-settled into golf. I really don't enjoy this at all.
You bring up Sand Hills. To me, that routing is wonderful. Hole out, begin your ride/walk to the next hole. The transitions aren't too long, however sometimes they are up hill, sometimes they are a bit long, but the hole time the vibe of the course and flow is maintained. The environment never changes, so mentally you stay in the round the entire time.
Again, 2 cents...take it or leave it.