Agree with what LindaLV has said, but want to be sure you're not talking about a domain name. Hyphens used when referencing a file or folder name is good. Hyphens in a domain name is less than ideal.

So, for example,

http://www.domainname.com/folder-name/file-name.html is good,

http://www.domain-name.com/foldername/filename.html is not so good.

Domain names should be short, memorable, preferably branded, and use no special characters.

As Russ states, you're far better off to just use language naturally. Google will figure it out. Stop words aren't going to prevent you from outranking the competition. A combination of other factors will, most notably the quantity and quality of incoming links to the page.

What pages are folks landing on when they do a local search? If it's the services page, you'll lose the ability to rank for those pages locally if you do a canonical. Are you showing up for local search terms in organic search results or local search results? If you go with a single site and dedicated local pages with local phone numbers, you'll be able to rank in both organic and local search results.

If your facility pages "tend to perform about the same as other local companies that are our biggest competition" and your goal is to gain an advantage, I'm thinking your best bet might be to grow your citations and reviews. I'm usually a big fan of consolidation so you can maximize the value derived from your SEO efforts, but it would be very disruptive to transition to a single site. Is management prepared and willing to shoulder that?

If you're not ready to rock the just boat yet, perhaps you should do an apples to apples comparison of your local facility sites to your competitors to see if a boost in citations or reviews could help bump you higher.

I'm just not hearing a pressing need from you...

Let's just do the math.

Let's say you can productively work 8 hours a day, 21 days a month. That's 168 hours total.

Divide that by 55 clients and you get 3 hours a month.

I haven't added in any extra time for your "junior" as he/she is probably already using up some of your 168 hours as it is in managing, mentoring, training time.

There is no way you can achieve anything measurable on 3 hours a month, regardless of what the client has signed up for, regardless of the role and responsibilities you've been assigned. Furthermore, if you flip it around the other way, would you want to accept a client that was only willing to pay you 3 hours a month with the expectation that you could "move the needle"? I know I wouldn't.

I'm not a fan of your plan.

There can be many reasons why a site might "take a hit". For example, if page-to-page redirects were not implemented or the sitemap was not updated, updated correctly, or resubmitted to search engines. I wouldn't assume that will happen in your case. In my experience, if the transition is done correctly and there's a hit, it's short-lived.

If you're thinking the redirects will cause you to lose SEO equity, that is no longer the case. Gary Illyes, a Google webmaster trends analyst, tweeted on July 26, 2016 "30x redirects don’t lose PageRank anymore."

One of the biggest risks (in my mind) of staging the migration the way you suggest is that the "waves" never happen. I see that a lot - a situation where an organization agrees to postpone work to a future date that never arrives. New and competing priorities take precedence resulting in an endless postponement. If you have the management commitment, funding and resources to do the work now, I say bite the bullet and go for it. Make a plan. Stick to it. Check and double check your work.

Matt-Antonino and Matt-Williamson have narrowed down two options that are highly respectable and well thought of - Bright Local and Whitespark. You should also consider Moz and Yext.

Moz offers a basic citation building service that helps you claim the most important listings – the ones that require manual verification. It gives you quick and easy access to all the local data aggregators (the sites that feed a majority of local directories). It's the most affordable.

Yext is limited in it's reach and least affordable. It will however, get your citations built fastest.

Whitespark and Bright Local can get you the most citations. They're both reasonably priced, accurate, and can speed up or slow down according to your needs.

This previously asked, answered and Moz staff endorsed question on the Moz Q&A forum compares Moz Local vs Whitespark vs Yext. The discussion was prompted by a question about UK citation building services, but I think you'll find it helpful.

I wrote a post a while ago that compares local directory submission services that you might like simply because of the simple chart shared under recommendations. It compares your options at a glance.

This forum has a brief back-and-forth discussing Bright Local vs Whitespark. It's just one thread, so don't give it too much weight in your decision. But, depending on your need, I suggest searching for similar feedback on this subset of services, checking out their websites, and then making a decision.