What is your background in playing these games? Do you already know a lot of table-top and/or digital board games? A lot of the ideas come from the experience of knowing what is already out there and how that sits with the audience. As for asking people to join you for the visual presentation of things, feel free to look into the Classifieds section of this website.

Have you also considered making a beta version that you then pitch to a publisher? Below is a nice video talking about game development:

(Edit: On second thought, you probably already know this, but I'll keep the video up for others to see)

My point is just that you can both hire others as well as pitch your design or even work freelance (although freelance doesn't seem like something you were looking for). Just make the beta with whatever UI/Graphics that you know yourself, then let the other individual (or publishing company) deal with the finishing touches.

You could even try to look into learning graphics stuff yourself. If you research other games and do a couple of Youtube tutorials, you should get a minimum of visual arts competence in practically no time at all.