I've been asked recently what to practice at home when there just isn't time for everything. There is definitely not one answer to that question. What works for me on one day doesn't necessarily work the next....but here's a quick run-down on the most commn places that I break the primary series when I'm short on time or energy and just can't do it all.
If time is really short: 5 sun salutation A
A little bit more time: 5 A and 5 sun salutation B
...a side note...Pattabhi Jois once told David Williams that 5 A and 5 B should be considered the "daily minimum practice"
A little more time and energy: I add the fundamental standing poses (padangusthasana through parsvottanasana) on to the sun salutations and then do the closing sequence starting with backbends.
Another place I stop is after all the standing poses. I'll go to closing poses from there.
Lastly, I sometimes break off practice after navasana and go to the closing poses from there. It's another good stopping point for me if, for whatever reason, I'm not going all the way to the end.
No matter what I'm practicing, I always begin with sun saluations and end with rest.
This is just what has worked for me. Please chime in and share other ways that you make yoga practice fit within "real life"! :)