Does anyone have a recommendation for a reputable SEO services company? After I build my client sites I would like to refer them onto a decent company.
It depends on what you need done and what your clients have for a budget. If it is A/B Testing, Adwords, Content creation and optimization, keyword strategies, On page SEO, Local SEO, I might say that Joost de Valk (creator of WordPress SEO by Yoast - yoast.com) might be a good choice. Though I believe he might require a website audit before putting together a good strategy for your clients.
I usually do SEO and website audits, and provide content creation, On page and Local SEO.
You may also want to go to Facebook or LinkedIn and join some SEO groups, and ask around