In my experience, extra certifications are beneficial to Principals of companies who are trying to bolster their profile as they bid competitively for work. Often they are the ones sealing the Plans, overseeing the whole project and appear in the Bid package to prospective clients. If you are just a grunt PE such as myself and Clients rarely review or approve your resume, it matters little. What I have found is if there is a specific project I am supposed to be the project manager on, then my company will pay me to get whatever certification they think I need to make my resume more fancy when we bid that project. Otherwise, no one really cares. You may hear differently from others - and I am not discounting their professional achievements, but anyone in the industry knows many certifications out there are just smoke and mirrors. Certifications are there to boost your profile to otherwise ignorant clients. Trust me when I say most town supervisors looking to award that new Elementary School project to a design firm don't have the first clue what LEED AP is - but it sure sounds important, right?
Just my opinion and your mileage may vary. I would just not have any great expectations. Especially if you are doing this on your own coin and gumption. I would talk it over with your overseers and see what they think about you purusing extracurricular certs.
The only letters that matter are PE (and SE if you live in an area that lawfully requires it). I would recommend instead of taking the time and money to study for a certification exam - instead spend some time really writing up a good resume and profile. People want to know what you worked on and what you did. Engineers should never have one page profiles. List everything in detail. Writing a good resume is very tedious and time consuming but well worth it.
I think many people try to sum their backgrounds up with extra alphabet soup so they don't have to bother with a good profile. Personally, I am far to diverse in my experience to let PTOE sum me up in four letters.