So you think Google+ is dying, eh? Your stream seems to be drying up or decaying into a mundane trickle of banality. Well, I'm sorry to say this, but it's probably not Google+, it's you. You may be doing it wrong.
I'm no "SEO expert" or social media guru, but if you want Google+ to be a dynamic, inspiring, fascinating river of content and ideas for you, I suggest doing four things:
1) Understand yourself. Without a good understanding and appreciation of what you're passionate about, you'll meander among seemingly random posts, never finding that group of people who will light up G+ like a Christmas tree for you. If you can identify those topics that you most enjoy discussing, it will help you to find others who share that passion much more quickly and effectively. And those people are the point of social media platforms like Google+.
2) Engage. Now, you need to engage those people in a meaningful way. If you can start to do that, the conversations you'll begin having will make it easier to find even more people who can provide content of value to you. Engagement is more than punching the +1 button on the occasional pretty photo or commenting "Nice!" on a useful infographic. Engagement is also more than just making a lot of posts. Meaningful engagement means making substantive comments and interacting with others to enhance the intellectual value of a post -- or even over a series of posts -- whether it's yours or someone else's. In a nutshell, engagement requires conversation...there's no avoiding that.
3) Post publicly. This is a potentially confusing recommendation for some people, as they've come to believe that circles on G+ are meant to restrict the audience for your outgoing content. In some (rare) cases, that's true, such as when you want to keep a post private and give access to a small number of other people (e.g., close friends, family members, or a spouse). Personally, I use circles to limit the audience when I post photos of my kids, as I'd rather those not go floating about the Internet. But for more general content, restricting the audience hurts your ability to engage. For example, if you're posting a link to an interesting article about a new camera that's coming out, limiting that to being visible only to your Photography circle is a mistake. One reason is that you just can't be sure who is going to be interested in seeing that, and by restricting who gets to, you remove the possibility of serendipity. That guy who you circled because of his fascinating posts about cooking just might be looking for a new camera. Not letting him see that is actually a disservice. After all, if he's not looking for one, ignoring your post is as easy as, well, doing nothing. A better use for circles on G+ is for focusing your incoming content into sub-streams that are more homogeneous, which might make it easier to read if you're not bouncing around lots of different topics from incoming post to incoming post. Or, using circles to quickly catch up on what close friends and family are doing, whose posts might get lost in the torrent of those high-volume political activists you're following, is incredibly easy. So, use circles mostly just for two purposes: (a) restricting access to outgoing posts for privacy (not relevance) reasons, and (b) focusing/filtering your incoming content for easier reading.
4) Be consistent. Unless you're famous, it can be challenging to develop a social media community that you're comfortable engaging and sharing your online existence. It's going to be doubly difficult if you only pop in once or twice a week for a little while. While you may only be following a few (dozen/hundred) people, many of those who you want to see your original thoughts, reshared posts, or external links follow lots of people. As a result, your post might just be another drop in their otherwise fast-moving stream. I've not seen too many people satisfied with the quality of their G+ experiences who don't interact at least several times a week, if not daily. It doesn't need to be obsessive, but consistent attention matters a lot. Assuming you are making posts and comments people enjoy, the more frequently people see you (or, more accurately, your avatar), the more they'll start to value your presence in their stream and the more they'll engage you back. If you only appear once every blue moon, you'll never develop enough social persistence to become an indispensable thread in their online social fabric.
To sum up, I've found Google+ to be a rich, dynamic, and rewarding social network. But, to make the most of it, you'll need to do some introspection and understand what floats your boat; meaningfully engage those with similar passions; post publicly as much of your content as can be safely shared; and do all that regularly. If you do, I think you'll find Google+ quickly becoming a cherished part of your online, social experience.