Well, having recently been in the job market, here's the impression I got--
It looks to me like out of the Unix certs, Solaris is by far the most widely tested for, and AIX is the rarest one. Which means, while Solaris certified people are still rare, there are still a good amount of them out there compared to the other two flavors--not to mention, it seems like a lot more people claim proficiency in Solaris over HP or AIX.
What I would recommend is, get AIX and/or HP-UX. I ended up getting all three, cause it's great to be able to claim to be competent at the three biggest brands out there, but AIX and HP are still a killer combo.
Oh yeah, and when he said 1100+ questions, you can see on the front page of their website that they advertise having something like 1150 questions in their study materials. 80 is the number of questions on the official HP-UX certification exam you take to get certified.