Thats' what I'm working now. Open guard. All flavours.
We recently did a bit of work ont the Z guard. This kind of came in handy, as I found I got to that position a whole lot anyway. But of course I didn't know what do do with it.... So now I have a nifty arm-drag, a sweep and some other stuff. And with that came a better understanding of how to deal with someone else's Z guard.
I've just started playing with the DLR guard as well. That's very much unknown territory, but I figure I have all the time in the world to experiment. I want to get away from just playing closed guard all the time. Sure, that means I'll get passed a lot. But so what.
I've had complaints about my half guard (bottom). I seem to escape from all sorts of positions to half guard. Often, it seems, I totally frustrate people because they work so hard to get past my halfguard, just to find that I've already got it back on them on the other side. Ok, so that's good. But I still felt like I was getting stuck there. Oh sure, bottom half is better than being mounted or having someone on my back. But I didn't seem to be able to capitalise on it much. Still, having spent so much time there, it certainly has given me plenty of time to work with the position.
I had an interesting discussion about this with Sensei. I mentioned that I feel I get there easy enough, and I'm happy about that, BUT that I can't do much with it. He said that in addition to learning attacks and sweeps from there, I need to change the way I look at it. Rather than saying "I ended up there", I should say "That's what I want" and "see, I got it!" and "now I'm attacking". We've already been working a fair bit on the deep half, which has helped me a lot. I am having a fair bit of success with it now.
I know that with a lot of the stuff I try, I fail because I don't commit, because I don't really believe I can do it. Same same for bottom half and entry to deep half. Once I can get around to viewing it as a starting point rather than a stalling point, I will be able to capitalise on it much more. BJJ is such a mental game. I sometimes wonder if it pushes the physical boundaries more or the mental ones. Either way, I'm forced to step outside my comfort zone remarkably often, and that is a good thing.